UNIVERSITY  OF  CALIFORNIA 
LOS  ANGELES 


AGRICULTURAL    PUBLICATIONS 
C.  V.  PIPER,  CONSULTING  EDITOR 


LABORATORY  MANUAL 

OF 
FRUIT  AND  VEGETABLE  PRODUCTS 


PUBLISHERS     OF     BOOKS     F  O  R^ 

Electrical  World  *?  Engineering  News-Record 
Power  v  Engineering  and  Mining  Journal-Press 
Chemical  and  Metallurgical  Engineering 
Electric  Railway  Journal  v  Coal  Age 
American  Machinist v  Ingenieria  Internacional 
Electrical  Merchandising  v  BusTransportation 
Journal  of  Electricity  and  Western  Industry 
:  Industrial  Engineer 


LABORATORY  MANUAL 

OF 

FRUIT  AND  VEGETABLE 
PRODUCTS 


AGRICULTURAL 
BY  UBRARV 

UCR 


W.  V.  CRUESS,  B.  S. 

ASSOCIATE  PROFESSOR  OF  FRUIT  PRODUCTS 
UNIVERSITY  OF  CALIFORNIA  COLLEGE  OF  AGRICULTURE 

AND 
A.  W.  CHRISTIE,  M.  S. 

ASSISTANT  PROFESSOR  OF  FRUIT  PRODUCTS 
UNIVERSITY  OF  CALIFORNIA  COLLEGE  OF  AGRICULTURE 


AGRICULTURAL  LIBRARY 


FIRST  EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 
NEW  YORK:  370  SEVENTH  AVENUE 

LONDON:  6  &  8  BOUVERIE  ST.,  E.  C.  4 

1922 


COPYRIGHT,  1922,  BY  THE 
McGRAW-HiLL  BOOK  COMPANY,  INC. 

AGRIC.  DEfT. 


Agric.  Dept, 


PREFACE 

Although  food  preservation  has  been  definitely  correlated  with  the 
development  of  modern  civilization,  it  has  been  one  of  the  last  of  the 
arts  to  attract  the  attention  of  scientific  men.  It  is  only  within  the  past 
thirty  years  that  the  principles  and  practices  of  food  preservation  have 
received  the  intelligent  investigation  which  they  merit.  Although  there 
are  yet  many  problems  demanding  solution,  much  has  been  accomplished 
toward  an  exact  understanding  of  the  scientific  principles  underlying  the 
manufacture  of  food  products. 

The  preparation  and  preservation  of  fruit  and  vegetable  products  have 
become  of  great  economic  importance,  but  this  subject  has  not  received 
the  attention  it  deserves  in  the  curricula  of  educational  institutions.  In 
many  horticultural  industries,  manufacturing  and  marketing  have  become 
of  as  great  importance  as  production.  There  is  a  rapidly  growing  demand 
for  persons  trained  in  the  scientific  principles  underlying  these  industries. 
Practical  knowledge  alone  no  longer  suffices. 

This  manual  meets  the  need  for  a  reliable  guide  in  laboratory  courses 
in  colleges  of  agriculture,  schools  of  domestic  science,  etc.,  in  the  manu- 
facture, preservation  and  examination  of  fruit  and  vegetable  products. 
It  is  the  outgrowth  of  a  course  given  at  the  University  of  California 
during  the  past  eleven  years. 

The  Assignments  are  designed  to  simulate  as  closely  as  is  possible  on 
a  small  scale  present  commercial  practices  as  well  as  to  illustrate  the 
fundamental  scientific  principles  involved.  Although  this  manual  should 
be  supplemented  by  lectures  or  books  giving  correlated  information,  much 
valuable  data  are  included,  especially  in  tabular  form. 

Although  intended  primarily  for  use  in  Agricultural  Colleges  and 
Domestic  Science  schools,  much  of  the  information  given  is  of  value  to 
growers,  manufacturers  of  fruit  and  vegetable  products,  food  inspectors 
and  chemists,  home  demonstration  agents  and  girls'  club  leaders,  and 
teachers  of  Agriculture  and  of  Domestic  Science  in  secondary  schools. 

WILLIAM  V.  CRUESS. 

ARTHUR  W.  CHRISTIE. 
BERKELEY,  CAL. 

>  1922 


CONTENTS 


PAGE 
v 


PREFACE   

ASSIGNMENT 

I.  Determination  of  the  Grade  of  Commercial!}7  Canned  Fruits    ...  1 

II.  Examination  of  Sound  and  Spoiled  Canned  Fruits  and  Vegetables  .     .  5 

III.  Experimental  Canning  of  Fruit 9 

IV.  Practice  in  Fruit  Canning 15 

V.  Determination  of  the  Grade  of  Commercially  Canned  Vegetables  .     .  17 

VI.    Experimental  Canning  of  Vegetables 20 

VII.    Practice  in  Vegetable  Canning 22 

VIII.    Examination  of  Tomato  Products 25 

IX.    Experimental  Preparation  of  Tomato  Puree 31 

X.    Practice  in  the  Preparation  of  Tomato  Products 32 

XI.    Examination  of  Commercial  Fruit  Juices 35 

XII.    Experimental  Preparation  of  Fruit  Juices 37 

XIII.  Practice  in  the  Preparation  of  Fruit  Juices 40 

XIV.  Preparation  of  Fruit  Syrups 43 

XV.  Examination  of  Commercial  Jellies,  Jams,  Marmalades  and  Preserves  .  46 

XVI.    Experimental  Preparation  of  Jelly  and  Marmalade 48 

XVII.    Practice  in  the  Preparation  of  Jelly  and  Marmalade 51 

XVIII.    Experimental  Preparation  of  Pectin  and  Jelly  Stock 55 

XIX.    Practice  in  the  Preparation  of  Jam,  Butter  and  Paste 57 

XX.    Experimental  Preparation  of  Fruit  Preserves 59 

XXI.    Practice  in  the  Preparation  of  Fruit  Preserves 60 

XXII.     Practice  in  the  Preparation  of  Candied  Fruits 62 

XXIII.  Examination  of  Commercially  Dried  Fruits  and  Vegetables  ....  64 

XXIV.  Experimental  Drying  of  Fruits  and  Vegetables 68 

XXV.     Practice  in  Fruit  and  Vegetable  Drying 72 

XXVI.     Practice  in  the  Preparation  and  Refining  of  Fixed  Oils 75 

XXVII.     Practice  in  the  Preparation  of  Essential  Oils 77 

XXVIII.     Examination  of  Commercial  Vinegars 80 

XXIX.    Experimental  Preparation  of  Cider  Vinegar 82 

XXX.    Practice  in  the  Preparation  of  Fruit  Vinegars 84 

XXXI.    Practice  in  the  Preparation  of  Sauerkraut  and  Pickles 86 

XXXII.     Practice  in  the  Preparation  of  Fruit  Acids 89 

XXXIII.  Practice  in  Olive  Pickling 92 

XXXIV.  Practice  in  the  Preparation  of  Museum  Specimens 95 

METHODS  OF  ANALYSIS 97 

SELECTED  REFERENCES 107 

INDEX  .  , Ill 


vn 


LABORATORY  MANUAL 

OF 

FRUIT  AND  VEGETABLE  PRODUCTS 

ASSIGNMENT  I.— DETERMINATION   OF  THE   GRADE   OF 
COMMERCIALLY  CANNED  FRUITS 

Materials. — Cans  of  each  of  the  different  grades  of  the  more  impor- 
tant canned  fruits,  such  as  cling-stone  peaches,  free-stone  peaches, 
apricots,  pears,  cherries,  strawberries,  blackberries,  and  olives. 

Procedure : 

1.  Weigh  the  can. 

2.  Cut  the  can  and  empty  the  contents  on  a  piece  of  Vs-inch  mesh 
screen  and  drain  for  at  least  two  minutes.    Weigh  the  drained  fruit  and 
measure  the  volume  of  syrup.     Weigh  the  empty  can.     Compare  the 
drained  weights  with  those  given  in  the  Appendix,  Table  XV. 

3.  Count  the  number  of  pieces  of  all  fruits  except  berries. 

4.  Determine  the  Balling  degree  and  temperature  of  the  syrup.    By 
use  of  Table  XIII  in  the  Appendix  make  the  necessary  temperature 
correction.     Determine  the  Baume  degree  of  the  brine  from  the  olives. 

5.  Determine  the  acidity  of  the  syrup  as  directed  in  Methods  of 
Analysis,  page  98.    Apples  and  pears  contain  malic  acid,  grapes  tartaric 
acid,  and  other  fruits  citric  acid.     Determine  the  reaction  of  the  brine 
from  the  olives. 

6.  Carefully  note  and  compare  the  appearance   and   flavor  of  the 
fruit  and  syrup  for  the  different  grades. 

7.  Note  the  appearance  of  the  interior  of  the  can;  i.  e.,  whether  it 
shows  evidence  of  excessive  corrosion  or  the  accumulation  of  iron  or  tin 
oxide. 

8.  Determine  the  grade  of  each  sample  by  reference  to  the  Specifica- 
tions for  Canned  Fruits  and  Tables  I  and  II. 

9.  Ascertain  the  probable  concentration  of  syrup  added  at  the  time 
of  canning  to  the  different  grades  of  fruit  examined. 

l 


Suggestions:  •' 

SPECIFICATIONS  FOR  CALIFORNIA  CANNED  FRUITS 
(Adopted  by  the  Canners7  League  of  California) 

General  Description  of  Grades: 

Fancy  grade  or  superlative  quality  consists  of  fruit  of  very  fine  color, 
ripe  yet  retaining  its  form,  not  mushy,  free  from  blemishes,  with  the 
pieces  uniform  in  size  and  very  symmetrical. 


FIG.  1. — Balling  hydrometer,  cylinder  and  thermometer. 

Choice  grade  or  fine  quality  consists  of  fruit  of  fine  color,  ripe  yet 
retaining  its  form,  not  mushy,  free  from  blemishes,  with  the  pieces 
uniform  in  size  and  symmetrical. 

Standard  grade  or  good  quality  consists  of  fruit  of  reasonably  good 
color,  ripe  yet  not  mushy,  reasonably  free  from  blemishes,  with  the 
pieces  reasonably  uniform  in  size  and  reasonably  symmetrical. 


Second  grade  or  second  quality  consists  of  fruit  tolerably  free  from 
blemishes,  pieces  tolerably  uniform  in  size,  color  and  ripeness. 

Pie  grade  or  pie  quality  consists  of  wholesome  fruit  unsuited  for  the 
above  grades. 

Table  I  gives  the  number  of  pieces  per  No.  21/£  can  for  the  five  grades 
of  each  fruit  and  also  the  percentage  of  sugar  in  the  syrup  placed  in  the 
can. 


TABLE  I. — CONCENTRATION  OF  SYRUP  AND  NUMBER  OF  PIECES  PER  No.  2^  CAN  FOR 
CALIFORNIA  CANNED  FRUITS 


Apricots  (Halves) 

Pears  (Halves) 

Peaches  (Halves) 

Grade 

Pieces  per 
No.  2J^  can 

Per  cent 
sugar  in 
syrup  used 

Pieces  per 
No.  2^2  can 

Per  cent 
sugar  in 
syrup  used 

Pieces  per 
No.  2^i  can 

Per  cent 
sugar  in 
syrup  used 

Fancy  .  .  . 

24  or  less 

55 

6  to  12 

40 

6  to  12 

55 

Choice  .  .  . 

30  or  less 

40 

6  to  15 

30 

6  to  15 

40 

Standard. 

42  or  less 

25 

6  to  21 

20 

6  to  12 

25 

Second.  . 

No  limit 

10 

No  limit 

10 

No  limit 

10 

Pie  

No  limit 

0 

No  limit 

0 

No  limit 

o 

Cherries  (Black  or  White) 

Cherries  (Royal  Anne) 

Grapes 

Plums 

Grade 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Pieces  per 
No.  2]4  can 

sugar  in 
syrup  used 

Pieces  per 
No.  2^2  can 

sugar  in 
syrup  used 

sugar  in 
syrup  when 
canned 

sugar  in 
syrup  when 
canned 

Fancy  .  .  . 

Not  over  100 

40 

Not  over  85 

40 

40 

55 

Choice  .  .  . 

Not  over  125 

30 

Not  over  105 

30 

30 

40 

Standard 

Not  over  175 

20 

Not  over  145 

20 

20 

25 

Second  .  . 

No  limit 

10 

No  limit 

10 

10 

10 

Pie  

No  limit 

0 

No  limit 

0 

0 

0 

Canned  Fruit  Salad: — 

Count: — Contents  divisible  into  portions  approximately  uniform  as 
to  variety. 

Syrup: — Not  less  than  40  per  cent,  sugar. 

Description: — Color  of  fruit  to  be  good  for  each  variety;  ripe,  yet 
not  mushy,  and  free  from  blemishes  serious  for  the  grade;  pieces 
of  each  variety  of  fruit  to  be  uniform  in  size  and  symmetrical. 


LABORATORY  MANUAL 


Table  II  gives  the  relation  between  the  grade  of  the  fruit  and  the 
Balling  degree  of  the  syrup  after  canning.  This  is  known  among  canners 
as  the  "cut  out"  test  of  the  syrup. 

TABLE   II. — APPROXIMATE   CONCENTRATION   OF   SYRTJP   FROM   VARIOUS   GRADES   OF 
CANNED  FRUIT — "CuT  OUT  TEST" 

(Compiled  from  U.  S.  Dept.  Agr.  Bull.  196  by  A.  W.  Bitting) 


Fancy 

Choice 

Standard 

Second 

Pie 

Fruit 

Grade 

Grade 

Grade 

Grade 

Grade 

Balling 

Balling 

Balling 

Balling 

Balling 

Degree 

Degree 

Degree 

Degree 

Degree 

Apricots  (Royal)  

34 

27 

20 

14 

9 

Cherries  (Black  Tartarian). 

28 

23 

18 

14 

10 

Cherries  (Royal  Anne)  .... 

26 

22 

18 

15 

10 

Grapes  (Muscat)  

28 

24 

21 

17 

12 

Peaches  

31 

22 

17 

11 

9 

Pears  (Bartlett)  . 

25 

21 

16 

14 

11 

Plums  (Green  Gage''  

34 

27 

19 

13 

9 

TABLE  III. — COMMERCIAL  SIZE  GRADES  OF  CALIFORNIA  RIPE  OLIVES 


Grade  No.  per  Pound 

Small 120  to  135 

Medium 105  to  120 

Large 90  to  105 

Extra  Large 75  to    90 


Grade  No.  per  Pound 

Mammoth 65  to  75 

Giant 55  to  65 

Jumbo 45  to  55 

Colossal  .  ..35  to  45 


Ripe  olives  of  the  best  quality  should  have  a  uniformly  black  or  dark 
brown  skin.  The  flesh  should  be  tender,  but  not  soft,  light  in  color,  and 
should  not  adhere  tightly  to  the  pit. 


ASSIGNMENT   II.— EXAMINATION   OF   SOUND  AND 

SPOILED  CANNED  FRUITS  AND 

VEGETABLES 

Materials. — One  can  each  of  the  best  and  poorest  grades  of  several 
varieties  of  canned  fruits  and  vegetables,  including  tomatoes. 

Several  spoiled  cans  of  fruits  and  vegetables.  Samples  of  "flippers," 
"springers,"  "swells,"  "leakers,"  and  "flat  sours." 

Procedure : 

1.  Examination  of  Sound  Samples. — Determine  the  vacuum  within 
the  can  by  piercing  the  top  with  a  vacuum  can  tester.    Open  the  sound 
cans  of  fruits  and  vegetables  and  compare  the  different  grades  as  to 
appearance,  flavor  and  odor. 

Place  a  drop  of  syrup  or  brine  from  each  sample  on  a  microscope 
slide  and  cover  with  a  cover  glass.  Examine  carefully  under  the  high 
power  of  the  microscope  (500  or  1,000  diameters  magnification)  and 
compare  the  numbers  of  organisms  found  in  the  liquids  from  the  best 
and  poorest  grades  of  each  product.  In  similar  manner  mount,  examine 
and  compare  samples  of  the  pulp. 

2.  Examination  of  Spoiled  Samples. — Compare  external  appearance 
and  internal  pressure  of  a  "flipper,"  a  "springer"  and  a  "swell." 

Open  the  spoiled  samples  and  compare  the  appearance  of  each  with 
that  of  sound  samples.  Note  the  odor.  Do  not  taste  spoiled  canned  food, 
because  it  may  contain  Bacillus  botulinus  and  be  poisonous. 

Examine  the  syrup  or  brine  from  each  sample  under  the  high  power 
of  the  microscope.  Make  sketches  of  the  organisms  found.  Carefully 
compare  the  microscopical  appearance  of  the  organisms  found  in  the 
spoiled  canned  fruits  with  that  of  the  micro-organisms  from  the  spoiled 
canned  vegetables. 

3.  Examination  of  the  can: 

A.  By  Pumping. — Cut  a  circular  opening  in  one  end  of  the  unopened 
can  of  such  size  that  it  can  be  closed  later  by  soldering  on  a  cap.  Re- 
move the  contents  of  the  can  and  rinse  thoroughly.  Boil  the  can  in  water 
about  one  hour  and  again  rinse  and  drain.  Cans  with  rubber  gaskets 
should  be  dried  about  one  hour  at  175°F.  Paper  gasket  cans  need  not 
be  dried.  Solder  a  cap  over  the  opening  and  through  a  small  hole  in  this 
cap  admit  compressed  air.  At  intervals  of  5  pounds  pressure  submerge 
the  can  in  water  and  observe  carefully  for  escaping  bubbles.  The  maxi- 

5 


6  LABORATORY  MANUAL  OF 

mum  pressure  to  which  cans  may  be  subjected  without  "buckling"  de- 
pends on  the  size  of  the  can.  Number  10  cans  may  "buckle"  at  10  to  15 
pounds,  No.  3  cans  at  15  to  20  pounds,  and  No.  2  cans  at  30  pounds. 
Buckling  distorts  the  seams  and  causes  leaks  which  did  not  previously 
exist.  The  location  of  leaks  should  be  marked  and  the  can  examined  to 


FIG.  2. — Determining  vacuum  in  a  can. 

ascertain  the  nature  and  cause  of  the  leaks.     (A  special  apparatus  for 
"pumping"  cans  is  manufactured  by  the  American  Can  Company.) 

B.  By  Filing. — File  a  cross  section  through  the  crimped  edge  of  the 
can  a  short  distance  from  and  on  each  side  of  the  side  seam  of  the  can, 
using  a  three-cornered  file.  File  through  the  outer  sheet  of  tin-plate 
between  the  two  cross-section  cuts  and  then  press  the  end  "hook"  out  of 
the  seam.  This  will  reveal  the  condition  of  the  gasket  and  seam  and 


FRUIT  AND  VEGETABLE  PRODUCTS  7 

indicate  if  the  seam  was  properly  made.  Both  the  "factory"  end  and 
the  "cannery"  end  of  a  can  may  be  examined  to  locate  faulty  double 
seaming.  Any  seam  in  the  can  which  showed  a  leak  when  tested  in  A 
above  should  be  examined  carefully  by  filing  or  in  the  case  of  soldered 
seams  by  separating  the  tin  plate  sheets  and  noting  the  continuity  of  the 
solder  used  in  sealing. 

Suggestions : 

1.  Definitions. — A  "swell"  is  a  can  which  has  undergone  gaseous  de- 
composition by  micro-organisms  which  first  releases  the  vacuum  and 
then  causes  pressure  in  the  can. 

A  "springer"  is  a  can  the  ends  of  which  are  more  or  less  bulged,  owing 
to  the  pressure  of  hydrogen  gas  generated  by  chemical  action  of  the 
acid  on  the  contents  of  the  metal  of  the  container,  or  because  the  can  has 
been  overfilled  or  insufficiently  exhausted. 

A  "flipper"  is  a  springer  of  such  mild  character  that  the  head  of  the 
can  may  be  drawn  in  by  striking  the  end  of  the  can  on  a  hard  surface. 

The  term  "flat  sour"  may  be  used  to  cover  many  abnormalities  in 
canned  foods,  but  generally  to  designate  a  can  of  food  which  has  under- 
gone bacterial  decomposition  with  increase  of  acidity  but  without  gas 
formation.  Canned  corn  occasionally  becomes  "flat  sour." 

A  "leaker"  is  a  can  from  which  part  of  the  syrup  or  brine  has  exuded. 
Leaks  may  be  caused  by  external  injury,  by  internal  pressure,  by  cor- 
rosion or  by  faulty  sealing.  The  contents  of  a  "leaker"  may  or  may  not 
be  spoiled. 

2.  Centrifuging. — In  order  to  concentrate  the  micro-organisms  in  the 
syrup  or  brine  from  sound  samples,  a  small  portion  of  the  liquid  may  be 
placed  in  a  centrifuge  tube  and  subjected  to  centrifugal  action  for  a  few 
minutes.    The  sediment  will  contain  most  of  the  micro-organisms. 

3.  Staining. — Yeasts  and  molds  may  be  examined  very  satisfactorily 
without  staining.    Bacteria  may  be  seen  more  clearly  under  the  micro- 
scope if  stained.     Place  a  drop  of  the  liquid  on  a  glass  slide.     Dry  it, 
without  scorching,  above  a  small  gas  flame.    Fix  the  material  by  passing 
the  slide  quickly  through  the  flame  several  times.    Cover  with  a  drop  of 
carbol  fuchsin.     Heat  above  flame  until  steam  is  given  off.     Rinse  in 
running  water.     Dry  above  a  flame.     Examine  without  the  use  of  a 
cover  glass. 

4.  Spoilage  of  canned  fruit  is  usually  caused  by  yeasts  which  enter 
the  can  through  leaks  after  sterilizing  and  is  rarely  due  to  insufficient 
sterilization.     The  spoilage  of  canned  vegetables,  however,  is  usually 
caused   by    spore-bearing   bacteria    which    survive   the   temperature   of 
processing. 


8  LABORATORY  MANUAL 

5.  The  pie  grade  of  most  fruits  will  normally  contain  a  few  yeast 
cells  and  an  occasional  mold  filament.  The  poorer  grades  of  canned 
tomatoes  may  exhibit  a  considerable  number  of  mold  filaments  and  bac- 
teria. The  presence  of  a  large  number  of  mold  filaments  indicates  the 
use  of  decayed  material.  Large  numbers  of  yeasts  or  bacteria  in  sterile 
cans  of  food  indicate  that  swelled  cans  or  "flat  sours"  have  been  re- 
processed. 


ASSIGNMENT  III.— EXPERIMENTAL  CANNING  OF  FRUIT 

Materials. — About  25  pounds  of  firm  ripe  canning  peaches,  5  pounds 
of  firm  tart  apples,  and  5  pounds  of  firm  ripe  berries. 

Procedure: 

1.  Comparison  of  Methods  of  Peeling  Peaches. — A.  Peel  and  pit  by 
hand  enough  firm,  ripe  peaches  of  yellow  flesh  to  fill  one  can. 

B.  Halve  and  pit  a  similar  quantity  and  place  on  a  screen  tray  or  in 
a  wire  basket  in  live  steam  for  3  to  4  minutes.    Skins  of  ripe  free-stone 
canning  varieties  can  then  be  slipped  from  the  fruit. 

C.  Prepare  in  an  agate-ware  pot  a  lye  solution  containing  5  grams 
of  sodium  hydroxide  per  100  c.c.  of  water.     Heat  to  boiling.     Immerse 
single  halves  of  the  unpeeled  fruit  in  the  boiling  lye  10,  20  and  30 
seconds  respectively  and  rinse  thoroughly  in  running  water.     This  will 
determine  the  length  of  immersion  required  for  peeling.     Peel  enough 
fruit  by  this  method  to  fill  one  can.    Remove  all  trace  of  lye  from  the 
fruit  by  thorough  rinsing.     Record  the  loss  in  peeling  by  the  three 
methods.    Fill  the  cans  of  peeled  fruit  with  syrup  of  30°  Balling.     Ex- 
haust 5  minutes  in  live  steam;  seal  and  sterilize  20  minutes  at  212°F. 
After  48  hours  or  longer  examine  the  fruit  and  syrup  carefully  for  flavor 
and  appearance. 

2.  Effect  of  Concentration  of  Syrup. — Prepare  enough  of  each  of  the 
following  syrups  to  fill  one  can  of  peaches:  0°  Balling  (water),  10°,  20°, 
40°,  60°  Balling,  see  Table  IV.     Prepare  enough  fruit  to  fill  five  cans 
and  weigh  both  the  empty  and  filled  cans.    Heat  each  syrup  to  boiling; 
fill  into  the  respective  cans  and  seal.     Sterilize  for  the  length  of  time 
indicated  in  Table  VI;  remove  the  cans  and  chill  in  water.     Allow  to 
stand  about  one  week.    Determine  the  weight  of  drained  fruit  from  each 
can  and  the  volume  and  Balling  of  the  syrup.     Carefully  compare  the 
appearance,  texture  and  flavor  of  the  fruit  from  the  different  cans. 

3.  Effect  of  Type  of  Container  on  Quality  of  Canned  Fruit. — Weigh 
one  each  of  the  several  types  of  containers,  such  as  sanitary,  solder-top 
and  wax-top  cans  and  glass  jars.     Fill  each  with  peaches  and  weigh. 
Prepare  a  syrup  of  30°  Balling.     Heat  this  to  boiling  and  fill  the  glass 
jars  to  overflowing  and  the  cans  to  within  about  a  quarter  of  an  inch  of 
the  top.    Exhaust  the  solder-top  and  sanitary  cans  in  live  steam  for  5 
minutes  before  sealing.     Sterilize,  store  and  examine  as  in  Assignment 
III  C  2. 

A.  Sealing  Solder-Top  Cans.    Caution. — Do  not  fill  the  cans  above 
one-quarter  inch  below  the  cap. 

9 


10 


LABORATORY  MANUAL  OF 


(a)  Wipe  the  groove  dry  of  all  syrup  and  juice. 

(b)  Apply  the  cap  and  wipe  the  groove  and  edge  of  the  cap  with  a 
small  brush  dipped  in  soldering  fluid. 

(c)  Dip  a  hot  well-tinned  soldering  steel  momentarily  in  soldering 
fluid,  apply  to  the  can  and  melt  a  little  solder  in  the  groove. 


B 


D 


FIG.  3. — A,  Coring  knife;  B,  Pitting  spoon;  C,  Cutting  knife,  and  D,  Peeling  knife. 

(d)  Revolve  the  hot  steel  to  distribute  the  solder  evenly. 

(e)  Press  down  on  the  center  rod,  and  raise  the  steel  a  few  seconds 
to  permit  the  solder  to  harden. 

(/)  After  exhausting  the  can  wipe  the  vent  hole  and  seal  with  a  drop 
of  solder  applied  with  a  well-tinned  tipping  steel.    See  Fig.  4. 

B.  Sealing  a  Sanitary  Can. —  (a)   Place  the  lid  on  the  can  and  set 


FRUIT  AND  VEGETABLE  PRODUCTS 


11 


FKJ.  4. — Sealing  a  solder  top  can;  A.  Wiping  the  groove;  B.  Applying  soldering  fluid; 
C.  Melting  solder  in  groove;  D.  Sealing  on  cap;  E.  Allowing  solder  to  harden;  F.  Solder- 
ing vent  hole  (tipping). 


12 


LABORATORY  MANUAL  OF 


the  can  on  the  turn  table.    Raise  the  turn  table,  by  swinging  the  raising 
lever  slowly  toward  the  operator  until  it  will  go  no  farther.     Give  the 

(b)  Turn  the  crank  rapidly  and  at  the  same  time  push  the  seaming 
roll  lever  very  slowly  away  from  the  operator  to  bring  roll  Number  1 
against  the  top  of  the  can  until  it  will  go  in  no  farther. 

(c)  Continue  turning  the  crank  rapidly  and  pull  the  seaming  roll 
leveft-stewly  toirtird  the  operator  until  it  will  go  no  further,     (live  the 
crank  several  more  turns  and  remove  the  sealed  can.    See  Figs.  5  and  6. 


FIG.  5. — Hand  power  sealer  for  sanitary  cans. 

C.  Place  the  covers  on  the  wax  top  cans,  but  do  not  seal  with  wax 
until  after  sterilization. 

D.  Place  rubber  rings  and  covers  on  the  glass  jars,  but  do  not  seal 
tightly  until  after  sterilization. 

4.  Effect  of  Kind  of  Sugar. — Prepare  syrups  of  30°  Balling  from 
several  kinds  of  syrup,  such  as  highest  quality  of  glucose  syrup,  refined 
malt  syrup,  sorghum  syrup,  and  as  controls,  30°  Balling  syrups  from 
cane  sugar  and  beet  sugar.  Fruit  juices  may  also  be  used  instead  of 


FRUIT  AND  VEGETABLE  PRODUCTS 


13 


syrup.  Can  peaches  in  these  syrups,  sterilize,  store,  and  examine  as 
directed  under  Paragraph  2. 

5.  Effect  of  Temperature. — Prepare  four  cans  of  peaches,  weighing 
the  fruit  placed  in  each  can.  Add  a  boiling  20°  Balling  syrup  and  seal. 

Heat  at  the  following  temperatures  for  the  times  indicated: 

165°F.  for  30  minutes 
185°F.  for  25  minutes 
212 °F.  for  20  minutes 
230°F.  for  15  minutes  (under  pressure) 


Compound  Giiket 


fir*  Optrition  Roll 


Stand  Opwition  Roll 


FIG.  6. — Sealing  a  sanitary  can. 

Cool,  store  and  examine  as  in  Paragraph  2.  If  blackberries,  straw- 
berries or  raspberries  are  available,  repeat  the  above  tests  with  one  of 
these  fruits. 

6.  Effect  of  Exhausting. — Fill  three  cans  with  peeled,  cored  and  quar- 
tered apples  and  add  cold  water  to  fill  the  cans  to  \'\  inch  from  the  top. 
Seal  Can  No.  1.  Heat  Can  No.  2  in  water  at  180°F.  for  6  minutes  and 


14  LABORATORY  MANUAL 

seal.  Heat  Can  No.  3  in  boiling  water  6  minutes  and  seal.  Sterilize  the 
three  cans  for  the  time  given  in  Table  VI.  Store  the  cans  for  2  weeks 
and  examine  carefully  as  follows: 

Determine  the  vacuum  in  each  can  by  means  of  a  vacuum  can  tester. 
Open  the  cans  and  compare  the  amount  of  corrosion  of  the  tin  in  each, 
especially  at  the  water  line  near  the  top  of  the  can.  Compare  the  three 
samples  as  to  appearance,  flavor  and  texture. 

Suggestions: 

1.  If  apples  are  used  the  peelings  and  cores  should  be  weighed,  dried, 
again  weighed,  and  the  product  retained  for  subsequent  use  in  jellies  or 
preserves.    Pits  should  be  weighed,  dried  and  retained  for  the  preparation 
of  sweet  and  bitter  almond  oils. 

2.  When  several  syrups  of  different  strengths  are  required  it  is  con- 
venient to  make  a  sufficient  quantity  of  60  per  cent,  syrup  and  then 
dilute  portions  of  this  to  the  required  strengths  in  accordance  with  the 
proportions  given  in  Table  IV. 

TABLE  IV. — PREPARATION  OP  SYRUPS  FOR  CANNING 

To  make  5  gallons  of  60  per  cent  syrup  take  32  Ibs.,  3  oz.  (14.6  Kilograms)  of  sugar 
and  2  gals.,  2  qts.  and  y<i  pt.  (9754  cubic  centimeters)  of  water. 

896  c.c.  60  per  cent  syrup  plus  105  c.c.  water  gives  1,000  c.c.  55  per  cent  syrup 
796  c.c.  60  per  cent  syrup  plus  205  c.c.  water  gives  1,000  c.c.  50  per  cent  syrup 
701  c.c.  60  per  cent  syrup  plus  301  c.c.  water  gives  1,000  c.c.  45  per  cent  syrup 
609  c.c.  60  per  cent  syrup  plus  393  c.c.  water  gives  1,000  c.c.  40  per  cent  syrup 
522  c.c.  60  per  cent  syrup  plus  480  c.c.  water  gives  1,000  c.c.  35  per  cent  syrup 
438  c.c.  60  per  cent  syrup  plus  564  c.c.  water  gives  1,000  c.c.  30  per  cent  syrup 
357  c.c.  60  per  cent  syrup  plus  645  c.c.  water  gives  1,000  c.c.  25  per  cent  syrup 
280  c.c.  60  per  cent  syrup  plus  722  c.c.  water  gives  1,000  c.c.  20  per  cent  syrup 
206  c.c.  60  per  cent  syrup  plus  796  c.c.  water  gives  1,000  c.c.  15  per  cent  syrup 
134  c.c.  60  per  cent  syrup  plus  866  c.c.  water  gives  1,000  c.c.  10  per  cent  syrup 


ASSIGNMENT  IV.— PRACTICE  IN  FRUIT  CANNING 

Materials. — At  least  five  pounds  each  of  firm  ripe  fruits  such  as 
apples,  apricots,  plums,  cherries,  pears  and  berries. 

Procedure : 

1.  Preparation. — Weigh  the  fresh  fruit  and  prepare  for  canning  as 
follows : 

Apples:  Peel  and  core  by  mechanical  peeler.  Trim  and  quarter  by 
hand.  Hold  in  3  per  cent,  brine  to  prevent  darkening. 

Apricots:  Cut  in  half  and  remove  pit.  Make  a  clean  cut  on  line 
of  suture.  Do  not  break  or  tear  edges  of  halves. 

Berries:  Sort  out  defective  berries,  stems  and  leaves.  Stem  straw- 
berries. 

Cherries:  Remove  stems.  If  desired,  pits  may  be  removed  by  small 
hand  pitting  machine. 

Grapes:    Remove  all  stems  and  defective  berries. 

Peaches:  Halve  and  pit  as  for  apricots.  Peel  as  described  in 
Assignment  III. 

Pears:  Hand  peel,  halve,  core  and  stem.  Hold  in  3  per  cent,  brine 
to  prevent  darkening. 

Plums:    Remove  stems  and  defective  fruits. 

Weigh  the  prepared  fruit  in  each  case  and  calculate  the  percentage 
loss  in  preparation.  Wash  all  prepared  fruit  thoroughly. 

2.  Grading: 

A.  Quality:    Sort  the  fruit  according  to  quality  to  conform  as  nearly 
as  possible  to  the  five  grades  given  in  Table  I. 

B.  Size:    Peaches,  apricots,  cherries,  grapes  and  plums  are  graded 
for  size  by  a  series  of  vibrating  screens,  containing  circular  openings  of 
the  average  sizes  given  in  Tabic  V.     Because  of  their  shape  pears  are 
graded  by  hand.    If  a  mechanical  grader  is  not  available,  grading  may 
be   accomplished   by   use   of  a   board   containing   holes   of   the   proper 
diameter. 

3.  Filling  and  Syruping. — Fill  the  cans  with  fruit  and  add  the  proper 
degree  of  syrup  for  each  grade  as  specified  in  Table  I. 

4.  Exhausting  and  Scaling. — Exhaust  the  filled  cans  in  live  steam  or 
boiling  water  for  5  minutes.    Seal  the  cans  immediately  after  exhausting. 

5.  Sterilizing  and  Cooling. — Sterilize  the  cans  in  accordance  with  the 
time  periods  given  in  Table  VI.    Chill  the  cans  in  cold  water  and  store 
for  future  examination. 

15 


16 


LABORATORY  MANUAL 


6.  Examination. — After  one  week  or  longer  open  the  cans  and  ex- 
amine as  directed  in  Assignment  I.  Compare  the  results  with  the  data 
given  in  Tables  I  and  II. 

Suggestions. — Apricot  and  cherry  pits  should  be  air-dried,  weighed 
and  retained  for  the  preparation  of  fruit  kernel  oils  in  Assignment  XXVI. 

TABLE  V. — AVERAGE  DIAMETERS  OP  VARIOUS  GRADES  OP  CANNED  FRUITS 
(Thirty-Seconds  of  an  Inch) 


Fruit 

Fancy 

Choice 

Stand. 

Fruit 

Fancy 

Choice 

Stand. 

Apricots 

56/32 
29/32 
26/32 
26/32 

54/32 
28/32 
25/32 
25/32 

50/32 
22/32 
22/32 

24/32 

Peaches 

76/32 
56/32 
8-10* 

64/32 
50/32 
10-12* 

56/32 
42/32 
15-17* 

Cherries,  Royal  Anne  . 
Cherries,  Black  

Plums,  Green  Gage 
Pears,  Bartlett.  .  .  . 

Grapes,  Muscat  

*  Number  per  No.  2J^  Can. 
TABLE  VI. — APPROXIMATE  TIME  REQUIRED  FOR  STERILIZATION  OF  FRUITS  AT  212°  F 


Fruit 

No.  1  Tall 
Cans 

No.  2H, 
No.  3  and 
Wax  Top  Cans 

No.  10  Cans 

Quart    Glass 
Jars 

Apples  

Minutes 

10 

Minutes 

10 

Minutes 

15 

Minutes 

20 

Apricots         

8 

15 

25 

20 

Blackberries  

8 

12 

25 

20 

Cherries  

15 

20 

30 

30 

Currants  

8 

12 

25 

20 

Figs  

60 

60 

70 

75 

Gooseberries 

8 

12 

25 

20 

Grapes  

8 

10 

25 

20 

Loganberries   

8 

12 

25 

20 

Oranges  

8 

10 

25 

15 

Peaches  (soft)  

15 

20 

40 

25 

Peaches  (firm)  

20 

25 

40 

30 

Pears  

20 

25 

40 

30 

Plums             

10 

14 

25 

20 

Prunes  (fresh)  

10 

12 

25 

20 

Raspberries  

8 

12 

25 

20 

Rhubarb  

8 

12 

25 

20 

Strawberries  

8 

12 

25 

20 

ASSIGNMENT  V.— DETERMINATION  OF  THE  GRADE  OF 
COMMERCIALLY  CANNED  VEGETABLES 

Materials. — One  can  each  of  the  different  grades  of  several  important 
vegetables,  such  as  tomatoes,  corn,  peas,  string  beans  and  asparagus. 

Procedure: 

1.  Weigh  the  can. 

2.  Ascertain  the  vacuum  within  the  can  by  piercing  the  top  of  the 
can  with  a  vacuum  can  tester. 

3.  Open  the  can  and  empty  the  contents  on  a  piece  of  %-inch  mesh 
screen  and  drain  for  2  minutes.    Weigh  the  drained  vegetable  and  meas- 
ure the  volume  of  brine.    Weigh  the  empty  can.    Compare  the  drained 
weights  with  those  given  in  the  Appendix,  Table  XV. 

4.  In  asparagus,  count  the  number  of  spears;  in  peas  or  beans,  ascer- 
tain the  average  diameter  of  the  pieces. 

5.  Compare  the  different  grades  of  each  vegetable   for    (a)    color, 
(6)   odor,   (c)   condition  of  pieces;  that  is,  whether  whole  or  broken; 
prime,  over-mature  or  immature;  soft  or  firm;  (d)  flavor. 

6.  Note  the  clearness,  color  and  general  appearance  of  the  brine. 
Determine  its  specific  gravity  or  Baume  degree.    If  desired,  the  amount 
of  salt  in  the  brine  may  be  determined  as  outlined  on  page  98  of  Ap- 
pendix.   Where  a  sugar  brine  has  been  used  the  concentration  of  sugar 
may  be  determined  as  described  on  page  100  of  Appendix. 

7.  Note  the  condition  of  the  interior  of  the  can. 

Suggestions. — The  commercial  grades  of  canned  vegetables  are  not 
as  well  standardized  as  those  of  canned  fruits.  The  following  specifica- 
tions describe  the  most  common  commercial  grades  and  form  a  guide 
in  determining  the  grade  of  the  samples  examined. 

GRADES  OF  CANNED  VEGETABLES 
Corn: 

A.  Styles: 

1.  Maine  style — thick  and  creamy  consistency  without  separation  of 
liquid.     (Can  not  be  labelled  "Maine  Style"  unless  canned  in  Maine.) 

2.  Maryland  style — whole  grains  in  clear  brine. 

B.  Grades: 

1.  Fancy — young,  tender,  no  tough  grains,  medium  moist,  free  from 
silk,  cob  or  husk.  Flavor  of  young  corn.  Only  slightly  darker  than 
natural  product. 

17 


18  LABORATORY  MANUAL  OF 

2.  Extra  Standard — corn  with  some  slight  defect,  but  better  than 
standard  grade  as  described  below. 

3.  Standard — reasonably  tender,  only  slightly  brown  in  color,  nearly 
free  from  silk,  cob  or  husk.    Only  slight  "cooked  taste." 

4.  Second — hard,  tough  grains  of  poor  flavor  or  appearance. 

Peas  : 

A.  Varieties: 

1.  Early  Peas — small,  smooth,  round. 

2.  Sweet  Peas — wrinkled,  irregular  in  shape,  later  maturing,  distinctly 
sweet. 

B.  Size  Grades: 

No.  Common  Name  Diameter  in  Inches 

1  Petit  Pois  Below  9/32 

2  Extra  Sifted  9/32  to  10/32 

3  Sifted  10/32  to  11/32 

4  Early  June  11/32  to  12/32 

5  Marrowfat  12/32  to  13/32 

6  Telephone  Over  13/32 

C.  Quality  Grades: 

1.  Fancy — young,  succulent,  fairly  uniform  in  size  and  color,  reason- 
ably clear  liquor,  no  flavor  defects. 

2.  Standard — less  succulent,  green,  mellow  consistency,  uniform  in 
size  and  color,  reasonably  clear  liquor,  fairly  free  from  flavor  defects. 

3.  Seconds — over-mature,  not  fully  ripened  or  lacking  in  other  re- 
spects the  qualifications  of  standard  peas. 

Beans  (string,  green  or  wax): 

A.  Size  Grades: 

No.  1,  less  than  12/64  inch  diameter  |  „    ,     ,     ,    , 

No.  2, 12/64  to  14/64  inch  diameter  J 

No.  3, 14/64  to  17/64  inch  diameter   } 

No.  4, 17/64  to  20/64  inch  >Cut  beans 

No.  5,  over  20/64  inch  j 

B.  Quality  Grades: 

1.  Fancy- — prime  beans,  uniform  and  tender  in  quality,  good  flavor 
and  color,  carefully  handled  and  canned,  clear  brine. 

2.  Extra  Standard — not  equal  to  fancy  grade  because  of  a  slight 
defect. 

3.  Standard — good  field  run  beans  of  less  uniform  selection.    May  be 
slightly  discolored  or  broken. 

4.  Seconds — wholesome  beans  which  may  be  coarse,  tough,  poorly 
stringed  or  with  foreign  flavor. 


FRUIT  AND  VEGETABLE  PRODUCTS 


19 


Tomatoes: 

A.  Types: 

1.  Solid  Pack  Tomatoes — peeled  and  cored  tomatoes  canned  whole 
or  in  large  pieces  without  addition  of  any  liquid. 

2.  Tomatoes  in  Puree — peeled  and  cored  tomatoes,  generally  smaller 
pieces  to  which  has  been  added  puree  made  from  whole  tomatoes  or  from 
trimmings  of  tomatoes. 

B.  Grades: 

1.  Extra  Fancy — ripe  fruit  of  uniform  red  color,  well-developed  flavor 
and  fleshy  body.    Mostly  whole  tomatoes  free  from  peel,  cores  or  defects. 

2.  Extra  Standard — ripe  fruit  of  fairly  fleshy  body,  good  flavor  and 
few  yellow  or  green  pieces.    Mostly  large  pieces,  well  peeled,  cored  and 
trimmed. 

3.  Standard  Tomatoes — fully  matured,  sound  fruit  of  fair  body  and 
flavor.     Broken  pieces  of  irregular  color,  but  well  peeled,   cored  and 
trimmed. 

4.  Seconds — a  mixture  of  green,  immature  pieces  and  soft,  over-ripe 
tomatoes. 

Asparagus: 

California  asparagus  is  graded  by  hand  according  to  the  number  of 
spears  per  can.  Each  size  grade  is  further  graded  into  white  and  green 
asparagus. 


Grade 

Size  of  Can 

Xo.  Spears  per  Can 

Giant    

2*4  Square* 

8  to  12 

Colossal         

2]^,  Square 

13  to  16 

Mammoth  

2^2,  Square 

17  to  24 

Mammoth         

1,  Square  —  Tips* 

21  to  30 

I  >H  rut  •               

2\^,  Square 

25  to  34 

Large 

1,  Square  —  Tips 

31  to  40 

Medium                 

2]/z,  Square 

35  to  44 

Medium                 

1,  Square  —  Tips 

41  to  60 

Small          

2H,  Square 

45  to  60 

Small                    

1,  Square  —  Tips 

61  to  80 

Tiny                  

1,  Square  —  Tips 

81  to  100 

*  No.  1,  Square  Can  is  3X3HX3>6  inches;  No.  2J&  Square  Can  is  3X3^X6^  inches. 

Beets: 

Beets  should  be  tender  and  without  large  vascular  zones  and  of  a 
uniform  deep  red  color  throughout. 

1.  Small — below  1  inch  diameter. 

2.  Medium. — 1  to  1M>  inches  diameter. 

3.  Large — I1/*  to  2  inches  diameter. 

4.  Very  large — over  2  inches  diameter  (cut  beets). 


ASSIGNMENT  VI.— EXPERIMENTAL  CANNING  OF 
VEGETABLES 

Materials. — A  vegetable  of  high  acidity,  such  as  tomatoes  or  rhu- 
barb, and  a  vegetable  of  low  acidity,  such  as  string  beans,  peas,  or  corn. 

Procedure : 

1.  Preparation. — Prepare  the  raw  material  for  canning  as  directed  in 
Assignment  VII. 

2.  Effect  of  Composition  of  Vegetables  on  Sterilizing  Temperature. — 
Prepare  three  cans  each  of  an  acid  vegetable  (e.  g.,  tomatoes)  and  of  a 
vegetable  of  low  acidity.    Exhaust  the  cans  in  hot  water  at  175 °F.  for 
about  6  minutes;  seal  hot.     Heat  one  can  of  each  in  water  at  175°  to 
180°F.  for  30  minutes;  one  can  of  each  in  boiling  water  for  30  minutes 
and  one  can  of  each  at  240°F.  for  15  minutes.    Remove  the  cans  in  each 
instance  and  chill  in  water.     Place  the  cans  in  an  incubator  at  90°  to 
100°F.  for  2  weeks  and  note  the  condition  of  the  cans  and  contents. 

3.  Effect  of  Composition  of  Brine. — Prepare  six  cans  of  a  vegetable 
of  low  acidity,  such  as  peas  or  string  beans.    Fill  Can  No.  1  with  boiling 
2  per  cent,  brine;  No.  2  with  boiling  4  per  cent,  brine;  No.  3  with  a 
boiling  6  per  cent,  brine;  No.  4  with  2  per  cent,  brine  acidified  to  0.1 
per  cent,  acidity  with  lemon  juice  or  citric  acid;  No.  5  with  2  per  cent, 
brine  acidified  to  0.2  per  cent,  citric  acid;  and  No.  6  with  2  per  cent, 
brine  acidified  to  0.15  per  cent,  acetic  acid  with  distilled  vinegar.     (See 
page  98  in  Appendix  for  determination  of  acid.)     Exhaust  all  the  cans 
for  5  minutes  and  seal  hot.    Heat  all  the  cans  in  boiling  water  for  30 
minutes.    Remove  and  cool  in  water.    Incubate  all  the  cans  at  90°  to 
100°F.  for  2  weeks  and  examine. 

4.  Critical  Temperature. — Prepare  five  cans  each  of  tomatoes  and 
string  beans;  add  2  per  cent,  brine  to  the  string  beans;  exhaust  all  the 
cans  for  5  minutes  and  seal.    Heat  the  cans  for  1  hour  as  follows:  One 
can  at  212°F.;  one  can  at  240°F.;  one  can  at  250°F.    Cool  all  the  cans 
in  water.     After  48  hours  compare  the  quality  of  the  different  lots  in 
respect  to  texture,  color,  odor  and  flavor. 

5.  Intermittent  Sterilization. — Prepare  8  cans  of  a  vegetable  of  low 
acidity  in  2  per  cent,  brine.     Add  spore-bearing  cultures  of  Bacillus 
subtilis  or  other  harmless  spore-bearing  bacteria.     Exhaust  5  minutes 
and  seal.    Place  two  cans  in  cold  water  and  heat  to  boiling.     Boil  one 
hour.    Similarly,  boil  two  cans  ll/2  hours.    Similarly,  heat  two  cans  in 

20 


FRUIT  AND  VEGETABLE  PRODUCTS  21 

water  until  the  water  boils  and  boil  for  30  minutes  each  of  2  successive 
days.  Similarly,  heat  two  cans  for  30  minutes  on  each  of  three  succes- 
sive days.  Place  all  cans  in  an  incubator  at  90°  to  100°F.  for  2  weeks 
and  then  examine. 

Caution. — Spoiled  cans  of  vegetables  may  be  poisonous  and  must  not 
be  tasted. 

Suggestions. — The  presence  of  thermophilic  bacteria  which  have  sur- 
vived the  process  of  sterilization  can  be  ascertained  by  incubating  cans 
at  130°F.  for  two  weeks.  The  cans  will  become  "flat  sours"  if  thermo- 
philic bacteria  have  been  active. 


ASSIGNMENT  VII.— PRACTICE  IN  VEGETABLE  CANNING 

Materials. — At  least  five  pounds  each  of  such  vegetables  as  corn, 
peas,  pumpkin,  sweet  potatoes,  asparagus  and  spinach. 

Procedure: 

1.  Preparation. — Prepare  the  vegetables  as  directed  below,  and  deter- 
mine the  loss  in  preparation. 

Asparagus. — Cut  to  proper  length  for  containers. 

Corn. — Carefully  remove  all  husk  and  silk  as  well  as  worm-eaten 
portions.  Cut  kernels  from  cob  with  a  sharp,  thin-bladed  knife  and 
scrape  cobs. 

Beans  (Green,  String  or  Wax). — Snip  the  ends  of  beans  and  remove 
strings. 

Beets. — Cut  off  leaves,  retaining  1  inch  of  stems.  Do  not  cut  off 
roots.  Heat  in  retort  at  220°F.  for  20  to  25  minutes,  or  in  boiling  water. 
Remove  stems,  roots  and  skins. 

Peas. — Shell  from  pods. 

Peppers  or  Pimientos. — Place  in  a  wire  basket  and  dip  in  a  kettle 
of  boiling  cottonseed  oil  (about  400°F.)  until  peel  separates,  about  1  to  4 
minutes.  Wash  and  cool  in  water.  Strip  off  loosened  peel,  cut  out  stem 
and  scoop  out  core  and  seeds,  carefully  preserving  the  flesh  in  one  piece. 

Pumpkin. — Wash  thoroughly;  remove  stems;  chop  into  large  pieces; 
place  in  pans  in  a  retort  at  240°F.  for  20  minutes.  Separate  pulp  from 
skins,  seeds  and  fiber  by  rubbing  through  a  fine  screen.  Concentrate  to 
a  thick  consistency  in  a  steam-jacketed  kettle.  The  specific  gravity 
should  be  about  1.06  to  1.08. 

Potatoes,  Sweet. — Heat  in  a  retort  at  240°F.  for  9  to  12  minutes. 
Slip  the  skins  off  by  hand. 

Spinach. — Cut  off  crowns,  heavy  stalks  and  yellow  leaves.  Wash 
very  thoroughly  to  remove  adhering  soil. 

Tomatoes. — Remove  decayed  portions.  Wash  thoroughly.  Heat  in 
boiling  water  or  steam  about  one  minute.  Chill  in  cold  water.  Remove 
peels  and  cores. 

2.  Grading. — Grade  asparagus,  beans,  beets  and  peas  for  size  and 
quality  by  reference  to  Assignment  V. 

3.  Blanching  and  Pre-cooking. — Blanch  asparagus,  string  beans,  peas 
and  spinach  in  boiling  water  as  directed  in  Table  VII.     The  time  of 
blanching  is  regulated  by  the  size  and  maturity  of  the  product.     Thor- 
ough washing  should  always  follow  blanching. 

22 


FRUIT  AND  VEGETABLE  PRODUCTS 


23 


Corn. — Add  to  the  cut  corn  a  sweet  brine  containing  about  4  per  cent, 
sugar  and  2.5  per  cent,  salt,  at  the  rate  of  5  ounces  per  No.  2  can.  Mix 
thoroughly  and  cook  in  a  steam- jacketed  kettle  until  tender  and  the 
liquid  and  the  kernels  no  longer  separate. 

4.  Filling  and  Brining. — Corn,  pumpkin  and  sweet  potatoes:    The 
cans  should  be  filled  with  the  hot  vegetables  without  addition  of  brine. 
Pimientos  and  peppers  are  packed  solidly  and  may  be  canned  with  or 
without  brine.     Other  vegetables  may  be  placed  in  the  cans  cold  and 
the  cans  filled  with  hot  brine  of  the  composition  given  in  Table  VII. 

Use  lacquered  cans  for  beets,  pumpkin  and  sweet  potatoes. 

5.  Exhausting  and  Sealing. — Exhaust  the  filled  cans  in  live  steam 
for  the  periods  given  in  Table  VII.    Seal  immediately  after  exhausting. 

6.  Sterilization  and  Cooling. — Sterilize  the  hot  sealed  cans  at  the 
temperatures  and  times  given  in  Table  VII.     Cool  thoroughly  in  water 
immediately  after  sterilizing.     The  sterilizing  periods  and  temperatures 
given  in  Table  VII  vary  with  the  maturity  of  the  products  and  size  of 
the  can.    The  periods  given  are  for  non-agitating  sterilizers. 

7.  Storage  and  Examination. — Store  for  about  two  weeks  and  com- 
pare the  quality  with  that  of  samples  of  similar  commercial   canned 
products. 

TABLE  VII. — CANNING  SCHEDULE  FOR  VEGETABLES 


Vegetable 

Steaming  or 
Blanching 

Composition  of 
Brine 

Exhaust- 
ing 

Sterilizing  No.  2 
or  No.  3  Cans 

Temp. 

Minutes 

Per  cent 
Salt 

Per  cent 
Sugar 

Minutes 
at  212° 

Temp. 

Minutes 

Asparagus 

212° 
212° 
220° 

3-  5 
1-  9 
20 

2 

lK-2>£ 
0-2^ 

2-X 

2 

0  or  2 

8-12 
5-  G 
5-  6 

233° 
240° 
245° 
250° 
240° 

212° 
212° 
250° 
252° 
212° 

30 
30 
60 
75 
40 

35 
180 
90 
50 
30 

Beans,  string.  .  . 

4 
0-3 

Peas     

212° 

400°* 
240° 
240° 
212° 
212° 

3-15 

1-  4 
9-12 
20 
3-  6 

y^ 

6-11 

3-13 
12-18 

Peppers  or 
Pimientos.  .  .  . 
Potatoes,  Sweet  . 

3-tf 

8-11 
8-10 

•Cottonseed  Oil. 


24  LABORATORY  MANUAL 

TABLE  VIII. — RELATION  OP  STEAM  PRESSURE  TO  TEMPERATURE 


Pressure-  Pounds 
per  Square  Inch 

Temperature, 
0  Fahrenheit 

Pressure-Pounds 
per  Square  Inch 

Temperature, 
0  Fahrenheit 

1 

215.2 

9 

236.6 

2 

218.3 

10 

238.8 

3 

221.3 

11 

241.0 

4 

224.2 

12 

243.1 

5 

226.9 

13 

245.3 

6 

229.5 

14 

247.3 

7 

231.9 

15 

249.1 

8 

234.3 

16 

250.7 

ASSIGNMENT  VIII.— EXAMINATION  OF  TOMATO 

PRODUCTS 

Materials. — Samples  of  tomato  puree,  paste  and  catsup. 

Procedure : 

1.  Determination  of  Total  Solids. — A.  Official  Method:    Place  from 
2  to  4  grams  of  the  well-mixed  sample  in  an  accurately  weighed  flat- 
bottomed  dish  about  2%  inches  in  diameter,  spreading  thinly.     Accu- 
rately weigh  the  dish  and  sample.     Place  in  a  vacuum  oven  at  70°C. 
(158°F.)  for  4  hours  in  a  vacuum  equivalent  to  28  to  29  inches  mercury. 
Remove  from  the  oven  and  weigh  immediately.     The  loss  in  weight 
divided  by  the  weight  of  sample  multiplied  by  100  gives  the  percentage 
of  water  in  the  sample,  which  subtracted  from  100  gives  the  percentage 
of  total  solids. 

B.  Tentative  Method:  In  the  absence  of  a  vacuum  oven,  weigh  10 
grams  of  the  well-mixed  sample  into  a  weighed  flat-bottom  dish  Evapo- 
rate to  dryness  on  a  steam  bath  and  dry  4  hours  in  a  water-  or  steam- 
jacketed  oven  at  95°  to  100°C.  (203°  to  212°F.).  The  percentage  of 
total  solids  thus  obtained  should  be  multiplied  by  the  factor  1.085  to  give 
the  true  percentage. 

2.  Determination  of  Specific  Gravity. — A.  By  Pycnometer:    Weigh  a 
dry  and  empty  50-c.c.  pycnometer.     Fill  with  distilled  water  at  20°C. 
and  weigh.    The  difference  between  these  two  weights  gives  the  volume 
of  the  pycnometer  or  A.    Empty  the  pycnometer  and  weigh.    Add  about 
10  grams  of  well-mixed  sample  and  weigh.    The  difference  between  these 
two  weights  gives  the  exact  weight  of  the  sample  or  B.    Fill  with  distilled 
water  at  20°C.,  weigh  and  subtract  the  original  weight  of  the  dry  pyc- 
nometer.   Call  this  C.    C  minus  B  =  D,  the  volume  of  water  required 
to  fill  the  pycnometer  after  addition  of  the  sample.    A  minus  D  gives  E, 
the  volume  of  water  displaced  by  the  sample.    B  divided  by  E  gives  the 
specific  gravity  of  the  sample. 

B.  By  Hydrometer:  Fluid  samples  such  as  light  puree  can  be  filtered 
through  cloth  or  filter  paper  and  the  specific  gravity  of  the  clear  filtrate 
obtained  by  means  of  a  specific  gravity  hydrometer  at  20°C.  By  refer- 
ence to  Table  IX  the  specific  gravity  of  the  original  sample  may  be 
obtained. 

3.  Relation  of  Total  Solids  to  Specific  Gravity. — Table  IX  gives  the 

25 


26 


LABORATORY  MANUAL  OF 


relation  between  the  specific  gravity  of  tomato  puree,  the  specific  gravity 
of  the  filtrate  and  total  solids.  The  table  does  not  apply  to  tomato 
catsup  or  other  products  to  which  foreign  materials  have  been  added. 

4.  Microscopical  Examination. — A.  Estimation  of  Molds:  Fit  the  mi- 
croscope with  a  10X  (1  inch)  eye  piece  and  16-mm.  (2/3  inch)  objective. 
Place  a  stage  micrometer  under  the  objective  and  adjust  the  draw  tube 
until  the  field  of  vision  is  1.4  mm.  in  diameter.  This  equals  an  area  of 
1.5  square  mm.  The  larger  divisions  on  the  stage  micrometer  are  0.1 
mm.  and  the  smaller  divisions  .01  mm.  apart.  If  a  stage  micrometer  is 


FIG.  7. — Rulings  on  hsemetimeter  used  in  examining  tomato  products. 

not  available  a  hsemetimeter  may  be  used  to  measure  the  diameter  of 
the  field.  Each  small  square  of  the  haemetimeter  is  0.05  mm.  in  diame- 
ter. The  magnification  should  be  90  to  100  diameters. 

Spread  a  drop  of  the  well-mixed  sample  on  the  disc  of  a  Howard 
counting  chamber.  Cover  with  the  heavy  cover-glass  and  press  it  evenly 
against  the  slide.  This  forms  a  layer  of  material  one  millimeter  thick. 

Examine  carefully  50  separate  fields  for  mold  filaments.  This  will 
usually  require  two  mountings.  All  fields  showing  mold  filaments  aggre- 
gating one-sixth  or  more  of  the  diameter  of  the  field  are  considered 
positive.  Multiply  the  number  of  positive  fields  by  2  to  obtain  "Per- 
centage of  Fields  Showing  Mold."  In  the  examination  of  tomato  paste 


FRUIT  AND  VEGETABLE  PRODUCTS  27 

dilute  the  sample  in  the  proportion  of  2  c.c.  of  water  to  each  gram  of 
paste. 

B.  Yeasts  and  Spores:    Fit  the  microscope  with  a  10X  (1  inch)  eye 
piece  and  an  8-mm.  (1/3  inch)  objective.    This  gives  a  magnification  of 
about  200  diameters,  draw  tube  set  at  160  mm. 

Dilute  10  c.c.  of  puree  or  catsup  to  30  c.c.  with  water  or  paste  10 
grams  to  90  c.c.  Mix  thoroughly  and  allow  to  settle  a  few  minutes. 
Mount  a  drop  of  the  settled  liquid  on  the  disc  of  a  haemetimeter.  Cover 
with  a  large  cover-glass  and  press  evenly  against  the  slide. 

Count  the  number  of  mold  spores  and  yeast  cells  in  200  of  the  small 
squares  of  the  haemetimeter  represented  by  eight  blocks  of  25  squares 
each  marked  A  in  Fig.  7. 

Each  of  the  smallest  squares  is  .05  mm.  x  .05  mm.,  or  .0025  square 
mm.  in  area.  Since  the  liquid  is  0.1  mm.  in  depth  the  volume  of  liquid 
above  each  square  is  .00025  cubic  mm.  Therefore  the  volume  above  200 
squares  is  .00025  x  200  =  .05  cubic  mm.  or  1/20  cu.  mm.  Since  the  sam- 
ple was  diluted  to  one-third  its  original  concentration,  the  above  estima- 
tion represents  the  number  of  "Yeasts  and  Spores  per  1/60  cu.  mm." 

C.  Bacteria    (Howard  Method) :    Fit  the  microscope  with  a  12.5X 
eye  piece  and  4-mm.   (1/6  inch)   objective.     This  combination  gives  a 
magnification  of  570  at  draw  tube  setting  of  160  mm. 

Use  the  same  mounting  as  for  yeasts  and  spores.  Count  the  number 
of  distinct  rod-shaped  bacteria  in  25  small  squares;  i.  e.,  five  groups  of 
five  small  squares  each  represented  by  letter  B  in  Fig.  7.  Do  not  count 
spherical  forms.  Mount  two  more  samples  and  repeat  the  examination 
and  determine  the  average  number  of  bacteria  to  the  small  square. 

Since  one  small  square  represents  .00025 — i.  e.,  1/4,000  cubic  milli- 
meters of  liquid — one  bacterium  to  a  square  represents  4,000  per  cu.  mm., 
or  4,000,000  per  cubic  centimeter.  Since  the  sample  was  diluted  to  one- 
third  its  original  concentration,  one  bacterium  to  a  square  represents 
12,000,000  bacteria  per  cubic  centimeter  of  original  sample. 

D.  Bacteria   (Miller  Modification) :    Transfer  20  c.c.  of  the  sample 
to  a  100-c.c.  beaker;  add  2  c.c.  Loeffler's  methylene  blue  stain;  boil  3 
minutes;  add  2  c.c.  Ziehl-Nielsen  carbol-fuchsin  stain;  boil  3  minutes; 
allow  to  cool  slightly;  add  3  to  4  drops  of  formalin;  make  up  to  60  c.c. 
with  water;  mix  and  allow  to  settle.     Examine  as  in  Assignment  VIII 
4  C.     The  staining  renders  the  bacteria  more  clearly  visible. 

Suggestions: 

1.  Tomato  products  which,  upon  microscopic  examination  by  the 
above  methods,  show  66  per  cent,  or  more  positive  mold  fields,  or  yeast 
and  spores  in  excess  of  125  per  1/60  cu.  mm.  or  bacteria  in  excess  of 
100,000,000  per  c.c.,  are  subject  to  seizure  and  condemnation  under  the 


28 


LABORATORY  MANUAL  OF 


TABLE  IX.— RELATION  BETWEEN  TOTAL  SOLIDS  AND  SPECIFIC  GRAVITY  OF  TOMATO 

PULP  AND  FILTRATE* 


Per  cent 
Solids 
in  Pulp 

Specific  Gravity 
at  20°  C. 

Per  cent 
Solids 
in  Pulp 

Specific  Gravity 
at  20°  C. 

Per  cent 
Solids 
in  Pulp 

Specific  Gravity 
at  20°  C. 

Pulp 

Filtrate 

Pulp 

Filtrate 

Pulp 

Filtrate 

3.42 

1.0150 

1.0133 

5.38 

1.0228 

1.0209 

7.34 

1.0308 

1.0285 

3.47 

1.0152 

1.0136 

5.44 

1.0230 

1.0211 

7.40 

1.0310 

1.0287 

3.53 

1.0155 

1.0138 

5.49 

1.0233 

1.0213 

7.45 

1.0313 

1.0290 

3.58 

1.0157 

1.0140 

5.55 

1.0235 

1.0216 

7.51 

1.0315 

1.0292 

3.64 

1.0159 

1.0142 

5.60 

1.0237 

1.0218 

7.56 

1.0317 

1.0294 

3.70 

1.0161 

1.0144 

5.66 

1.0240 

1.0220 

7.62 

1  .  0320 

1.0296 

3.76 

1.0163 

1.0146 

5.72 

1.0242 

1.0223 

7.68 

1.0322 

1.0298 

3.81 

1.0166 

1.0149 

5.77 

1.0244 

1.0225 

7.74 

1.0324 

1.0300 

3.87 

1.0168 

1.0151 

5.83 

1.0247 

1.0227 

7.79 

1.0326 

1.0303 

3.92 

1.0170 

1.0153 

5.88 

1.0249 

1.0229 

7.85 

1.0329 

1.0305 

3.98 

1.0172 

1.0155 

5.94 

1.0251 

1.0231 

7.90 

1.0331 

1.0307 

4.03 

1.0174 

1.0157 

6.00 

1.0253 

1.0233 

7.96 

1.0333 

1.0309 

4.09 

1.0177 

1.0160 

6.05 

1.0256 

1.0235 

8.02 

1.0336 

1.0311 

4.15 

1.0179 

1.0162 

6.11 

1.0258 

1.0238 

8.07 

1  .  0338 

1.0313 

4.20 

1.0181 

1.0164 

6.16 

1.0260 

1.0240 

8.12 

1.0340 

1.0315 

4.26 

1.0183 

1.0166 

6.22 

1.0263 

1.0242 

8.18 

1.0342 

1.0318 

4.31 

1.0185 

1.0168 

6.28 

1.0265 

1.0244 

8.24 

1.0345 

1.0320 

4.37 

1.0188 

1.0170 

6.33 

1.0267 

1.0246 

8.30 

1.0347 

1.0322 

4.43 

1.0190 

1.0173 

6.39 

1.0270 

1.0249 

8.35 

1.0349 

1.0324 

4.48 

1.0192 

1.0175 

6.45 

1.0272 

1.0251 

8.40 

1.0352 

1.0326 

4.54 

1.0194 

1.0177 

6.50 

1.0274 

1.0253 

8.46 

1.0354 

1.0328 

4.59 

1.0197 

1.0179 

6.56 

1.0276 

1.0255 

8.52 

1.0356 

1.0331 

4.65 

1.0199 

1.0181 

6.61 

1.0279 

1.0257 

8.57 

1.0358 

1.0333 

4.71 

1.0201 

1.0183 

6.67 

1.0281 

1.0259 

8.63 

1.0361 

1.0335 

4.76 

1.0203 

1.0185 

6.72 

1.0283 

1.0261 

8.68 

1.0363 

1.0337 

4.82 

1.0205 

1.0188 

6.78 

1.0285 

1.0263 

8.74 

1.0365 

1.0339 

4.87 

1.0208 

1.0190 

6.84 

1.0288 

1.0266 

8.80 

1.0367 

1.0341 

4.93 

1.0210 

1.0192 

6.89 

1.0290 

1.0268 

8.86 

1  .  0370 

1.0344 

4.99 

1.0212 

1.0194 

6.95 

1.0292 

1.0270 

8.91 

1.0372 

1.0346 

5.04 

1.0215 

1.0196 

7.01 

1.0294 

1.0272 

8.96 

1.0374 

1.0348 

5.10 

1.0217 

1.0198 

7.06 

1.0297 

1.0274 

9.02 

1.0277 

1.0350 

5.16 

1.0219 

1.0200 

7.12 

1.0299 

1.0277 

9.08 

1.0379 

1.0352 

5.21 

1.0222 

1.0203 

7.17 

1.0301 

1.0279 

9.14 

1.0381 

1.0354 

5.27 

1.0224 

1.0205 

7.23 

1.0304 

1.0281 

9.19 

1.0383 

1.0357 

5.33 

1.0226 

1.0207 

7.28 

1.0306 

1.0283 

9.25 

1.0386 

1.0359 

*According  to  Bigelow  and  Fitzgerald  in  Journal  of  Industrial  and  Engineering 
Chemistry,  vol.  7,  No.  7,  page  602.    July,  1915. 


FRUIT  AND  VEGETABLE  PRODUCTS 
TABLE  IX. — Continued 


29 


Per  cent 
Solids 
in  Pulp 

Specific  Gravity 
at20°C. 

Per  cent 
Solids 
in  Pulp 

Specific  Gravity 
at  20°  C. 

Per  cent 
Solids 
in  Pulp 

Specific  Gravity 
at  20°  C. 

Pulp 

Filtrate 

Pulp 

Filtrate 

Pulp 

Filtrate 

9.30 

1.0388 

1.0361 

10.97 

1.0456 

1.0426 

12.65 

1.0524 

1.0491 

9.36 

1.0390 

1.0363 

11.02 

1.0458 

1.0428 

12.71 

1.0526 

1.0493 

9.42 

1.0393 

1.0366 

11.08 

1.0461 

1.0430 

12.77 

1.0528 

1.0495 

9.47 

1.0395 

1.0368 

11.14 

1.0463 

1.0433 

12.83 

1.0531 

1.0498 

9.53 

1.0397 

1.0370 

11.20 

1.0465 

1.0435 

12.88 

1.0533 

1.0500 

9.58 

1.0400 

1.0372 

11.25 

1.0467 

1.0437 

12.94 

1.0535 

1.0502 

9.64 

1.0402 

1.0374 

11.30 

1.0469 

1.0439 

12.99 

1.0538 

1.0504 

9.70 

1.0404 

1.0376 

11.36 

1.0472 

1.0441 

13.05 

1.0540 

1.0506 

9.75 

1.0406 

1.0379 

11.41 

1.0474 

1.0444 

13.10 

1.0542 

1.0508 

9.80 

1.0408 

1.0381 

11.47 

1.0476 

1.0446 

13.16 

1.0544 

1.0511 

9.86 

1.0410 

1.0383 

11.53 

1.0478 

1.0448 

13.22 

1.0547 

1.0513 

9.92 

1.0413 

1.0385 

11.59 

1.0481 

1.0450 

13.27 

1.0549 

1.0515 

9.97 

1.0415 

1.0387 

11.64 

1.0483 

1.0452 

13.32 

1.0551 

1.0517 

10.02 

1.0417 

1.0389 

11.70 

1.0485 

1.0454 

13.38 

1.0554 

1.0519 

10.08 

1.0419 

1.0392 

11.75 

1.0487 

1.0457 

13.44 

1.0556 

1.0521 

10.14 

1.0421 

1.0394 

11.81 

1.0490 

1.0459 

13.50 

1.0558 

1.0523 

10.19 

1.0424 

1.0396 

11.87 

1.0492 

1.0461 

13.55 

1.0560 

1.0525 

10.25 

1.0426 

1.0398 

11.93 

1.0494 

1.0463 

13.60 

1.0562 

1.0527 

10.30 

1.0428 

1.0400 

11.99 

1.0496 

1.0465 

13.66 

1.0565 

1.0529 

10.35 

1.0430 

1.0402 

12.05 

1.0499 

1.0467 

13.72 

1.0567 

1.0531 

10.41 

1.0433 

1.0404 

12.10 

1.0501 

1.0469 

13.78 

1.0569 

1.0533 

10.47 

1.0435 

1.0406 

12.15 

1.0503 

1.0471 

13.83 

1.0572 

1.0535 

10  52 

1.0437 

1.0409 

12.21 

1.0505 

1.0474 

13.89 

1.0574 

1.0537 

10  58 

1.0440 

1.0411 

12.26 

1.0508 

1.0476 

13.95 

1.0576 

1.0539 

10.64 

1.0442 

1.0413 

12.32 

1.0510 

1.0478 

14.01 

1.0579 

1.0241 

10  70 

1.0444 

1.0415 

12.37 

1.0512 

1.0480 

10.75 

1.0447 

1.0417 

12.43 

1.0515 

1.0482 

10.80 

1.0449 

1.0419 

12.49 

1.0517 

1.0484 

10.86 

1.0451 

1.0422 

12.55 

1.0519 

1.0487 

10.91 

1.0453 

1.0424 

12.60 

1.0522 

1.0489 

30  LABORATORY  MANUAL 

Federal  Pure  Foods  and  Drugs  Act  of  1906.  The  same  standards  have 
been  adopted  by  most  states. 

Investigations  have  shown  that  with  reasonable  care  and  promptness 
in  the  sorting  and  washing  of  tomatoes,  together  with  cleanliness  in  the 
care  of  equipment,  it  is  readily  possible  to  manufacture  tomato  products 
containing  numbers  of  micro-organisms  well  below  the  legal  limits. 

For  a  more  detailed  discussion  of  this  subject  consult  U.  S.  Dept.  Agr. 
Bull.  581. 

2.  No  legal  standards  for  the  specific  gravity  of  tomato  products 
have  been  adopted,  but  the  following  tentative  standards  have  been  sug- 
gested and  are  generally  observed  in  commercial  practice: 

Light  tomato  puree,  6.3  per  cent,  total  solids  =  1.026  spec,  gravity. 
Medium  tomato  puree,  8.37  per  cent,  total  solids  —  1.035  spec,  gravity. 
Heavy  tomato  puree,  12.00  per  cent,  total  solids  =  1.050  spec,  gravity. 
Tomato  catsup,  not  less  than  12  per  cent,  tomato  solids. 

3.  Benzoate  of  Soda. — Thin  catsups  low  in  acetic  acid  are  sometimes 
preserved  with  sodium  benzoate,  which  is  permitted  by  the  Food  and 
Drug  Regulations  if  the  presence  of  benzoate  is  declared  on  the  label. 
The  usual  quantity  is  0.1  per  cent.     The  presence  of  this  preservative 
can  be  detected  by  the  method  given  in  the  Appendix,  page  102. 


ASSIGNMENT    IX.— EXPERIMENTAL    PREPARATION    OF 

TOMATO  PUREE 

Materials. — About  50  pounds  of  field  run  tomatoes  with  at  least 
one-third  of  the  tomatoes  showing  mold. 

Procedure: 

1.  Carefully  separate  the  sound  tomatoes  from  those  showing  mold. 
Wash  the  sound  tomatoes.     Crush   and  pulp  these  tomatoes  without 
heating  and  divide  the  screened  pulp  into  two  portions.    Concentrate  one 
portion  at  once  to  a  specific  gravity  of  about  1.035  as  directed  in  Sec- 
tion 1,  Assignment  X.    Allow  the  other  portion  to  stand  for  one  day  or 
overnight  and  then  concentrate  in  the  same  way. 

2.  Rinse  but  do  not  trim  the  moldy  tomatoes  and  prepare  from  them 
puree  of  about  1.035  specific  gravity  as  described  in  Section  1,  Assign- 
ment X. 

3.  Determine  the  amounts  of  mold  and  of  bacteria  in  the  three  lots 
of  puree  as  described  in  Assignment  VIII.    Compare  the  results  obtained 
with  the  character  of  the  raw  material  and  the  methods  of  handling. 

Suggestions. — Save  the  tomato   seeds   as   directed   in   Suggestions, 
Assignment  X. 


31 


ASSIGNMENT  X.— PRACTICE  IN  THE  PREPARATION  OF 
TOMATO  PRODUCTS 

Materials. — Approximately  250  pounds  of  sound,  smooth,  evenly- 
ripened  tomatoes  of  deep-red  color,  firm  flesh  and  good  flavor. 

Procedure: 

1.  Medium  Puree. — Weigh  accurately;  sort  carefully;  trim  and  wash 
about  50  pounds  of  tomatoes.    Determine  the  loss  in  trimming. 

Crush  the  tomatoes  thoroughly  and  transfer  to  a  steam-jacketed 
kettle  or  large  aluminum  pot  and  boil  about  three  minutes. 

Pass  the  hot  pulp  through  the  finishing  screen  of  a  tomato  pulper  or 
rub  through  a  very  fine  copper  screen  by  hand  to  remove  the  seeds,  skins 
and  fiber. 

Return  the  pulp  to  the  kettle  or  large  pot  and  concentrate  rapidly 
with  constant  stirring  to  a  specific  gravity  of  1.035,  determined  as  di- 
rected below.  This  specific  gravity  corresponds  approximately  to  a 
concentration  of  3  parts  of  raw  pulp  to  2  parts  of  puree. 

RAPID  DETERMINATION  OF  SPECIFIC  GRAVITY 

Filter  a  sample  of  the  hot  pulp  through  cheese  cloth  into  a  hydrome- 
ter cylinder  packed  in  crushed  ice  and  salt.  Cool  the  filtrate  rapidly  to 
20°C.  (68°F.)  and  determine  the  specific  gravity  by  means  of  an  accu- 
rate hydrometer  or  Westphal  balance.  Obtain  the  corresponding  specific 
gravity  of  the  puree  from  Table  IX. 

Determine  the  volume  of  finished  puree.  Fill  several  16-oz.  bottles, 
plain  sanitary  cans  and  lacquered  cans  with  the  boiling-hot  puree.  Seal 
all  containers  immediately  and  invert,  using  crown  caps  for  the  bottles. 
Heat  two  of  the  plain  cans  in  boiling  water  or  steam  for  30  minutes. 
Store  all  samples  for  subsequent  examination. 

2.  Puree  for  Catsup. — Treat  a  carefully  weighed  quantity  of  toma- 
toes (about  50  pounds)  as  directed  in  Assignment  X  1,  but  concentrate  to 
a  specific  gravity  of  1.060.     Determine  the  yield  by  volume  and  by 
weight. 

Reserve  one  gallon  of  the  concentrated  puree  for  the  preparation  of 
catsup  in  Assignment  X  3.  Fill  one-half  of  the  remainder  boiling  hot  into 
lacquered  cans  and  one-half  boiling  hot  into  plain  tin  cans;  seal  at  once; 
invert  to  cool  and  set  aside  for  at  least  six  weeks.  Compare  these  sam- 

32 


FRUIT  AND  VEGETABLE  PRODUCTS  33 

pies  with  those  prepared  according  to  Assignment  X  1  for  color,  flavor  and 
consistency. 

3.  Tomato  Catsup  (Spiced  Vinegar  Process). — To  435  c.c.  of  distilled 
vinegar  of  10  per  cent,  acetic  acid  content  ("100  grain"  vinegar)   and 
132  c.c.  of  water  in  a  1,000-c.c.  flask  add  the  following  ingredients: 

Onions,  peeled  and  chopped . . .  105  grams  Allspice,  whole 4.5  grams 

Garlic,  peeled  and  chopped 1  gram  Cayenne  pepper,  ground 1      gram 

Cloves,  whole 4  grams  Mace,  not  ground t      gram 

Cinnamon,  whole 7  grams 

Connect  the  flask  to  a  reflux  condenser  or  cover  the  mouth  of  the 
flask  with  a  watch  glass  or  Petri  dish  and  allow  to  simmer  for  about  one 
hour.  Strain  through  cheese  cloth.  If  the  volume  is  less  than  570  c.c. 
add  water  to  restore  to  this  volume.  Dissolve  in  this  hot  spiced  vinegar 
585  grams  of  sugar  and  135  grams  of  salt.  Add-  this  spiced  vinegar  to 
one  gallon  (3,785  c.c.)  of  puree  of  about  1.060  specific  gravity.  Stir 
thoroughly,  heat  to  boiling  and  fill  hot  into  16-oz.  crown-finish  bottles. 
Seal  at  once  and  invert  to  cool.  Heat  two  of  the  bottles  in  boiling  water 
or  steam  for  30  minutes. 

Note  the  flavor,  color,  odor  and  consistency  after  six  weeks'  storage. 
A  specific  gravity  determination  may  be  made  if  desired. 

4.  Tomato  Catsup    (by  Direct  Extraction  of  Spices). — Place  in  a 
small  cheese-cloth  bag  the  same  quantities  of  spices,  onion  and  garlic 
as  used  in  Paragraph  3.    Tie  the  mouth  of  the  bag  and  place  it  in  three 
gallons  of  unconcentrated  raw  tomato  pulp.     Concentrate  by  boiling  to 
about  1.060  specific  gravity  (approximately  one  gallon).     Dissolve  585 
grams  of  sugar  and  135  grams  of  salt  in  435  c.c.  of  distilled  vinegar 
(100  grain)  and  132  c.c.  water.     Add  this  solution  to  the  concentrated 
hot  puree.     Stir  thoroughly,  heat  to  boiling,  remove  the  sack  of  spices 
and  fill  the  catsup  hot  into  16-oz.  crown-finish  bottles.     Determine  the 
approximate  yield.     Store  and  examine  as  under  Assignment  X  3. 

5.  Chili  Sauce.— To  380  c.c.  of  distilled  vinegar  (100  grain)  in  1,000 
c.c.  flask  add  the  following  ingredients: 

Onions,  chopped 363      grams 

Allspice,  whole 5.6  grams 

Cloves,  whole 5.6  grams 

Cinnamon,  sticks 6.6  grams 

and  allow  to  simmer  for  about  one  hour  as  in  Assignment  X  3,  and  strain 
through  cheese  cloth.  Dissolve  in  the  strained  liquid  636  grams  sugar 
and  136  grams  of  salt. 

Place  8,400  grams  whole  peeled  tomatoes  in  a  pot  and  concentrate 
to  approximately  4,000  c.c.  Then  add  5.6  grains  ground  cayenne  pepper 
and  1.4  grains  ground  mustard.  Concentrate  to  about  3,400  c.c.  and  add 


34  LABORATORY  MANUAL 

the  spiced  vinegar.  Stir  thoroughly.  Heat  to  boiling  and  seal  hot  in 
glass  fruit-jars.  Pasteurize  40  minutes  in  water  at  185°F.  Store  and 
examine  as  under  Assignment  X  3. 

6.  Hot  Sauce  (Spanish  Style). — To  6,205  c.c.  of  raw  non-concentrated 
pulp  (from  a  tomato  pulper)  add  the  following  ingredients,  finely 
ground : 

Onions 74      grams 

Ground  chili  peppers 112      grams 

Garlic 2.3  grams 

Concentrate  to  about  3,785  c.c.  Add  2.5  grams  ground  cayenne 
pepper  mixed  with  about  10  c.c.  of  water,  and  74  grams  of  salt.  Stir 
thoroughly.  Heat  to  boiling  and  fill  boiling  hot  into  small  cans.  Seal, 
store  and  examine  as  under  Assignment  X  3. 

Suggestions. — The  skins  and  seeds  separated  from  the  tomato  pulp 
should  be  collected  and  weighed,  after  which  this  material  should  be 
dried  at  a  moderate  temperature  in  a  dehydrater  or  over  a  radiator, 
weighed  again  and  the  skins  separated  from  the  seeds  by  fanning.  The 
dry,  clean  seed  should  be  retained  for  the  preparation  of  tomato-seed 
oil  as  directed  in  Assignment  XXVI. 


ASSIGNMENT  XI.— EXAMINATION  OF  COMMERCIAL 
FRUIT  JUICES 

Materials. — One  bottle  each  of  the  juice  of  the  following:  Eastern 
grape,  California  grape,  loganberry,  pineapple,  orange,  apple  and  lemon. 
One  can  of  pure  apple  juice  and  a  sample  of  apple  juice  preserved  with 
benzoate  of  soda. 

Procedure: 

1.  Appearance. — Before  opening  a  bottle  note  whether  the  juice  is 
brilliant,  clear,  hazy,  cloudy  or  muddy ;  whether  there  is  a  small,  medium 
or  large  amount  of  sediment  and  whether  this  deposit  is  amorphous  or 
crystalline.    Describe  the  color  of  the  juice. 

2.  Net  Contents. — Determine  the  volume  of  juice  in  each  container 
and  report  as  fluid  ounces.    Compare  with  the  net  contents  declared  on 
the  label. 

3.  Flavor  and  Odor. — Note  the  odor  of  the  juice,  especially  in  regard 
to  the  presence  or  absence  of  fresh-fruit  aroma  or  of  "cooked"  odor. 
Note  whether  the  flavor  is  fresh,  stale  or  "cooked."    Note  whether  the 
acid  and  sugar  are  agreeably  balanced.     Compare  the  flavor  of  apple 
juice  containing  benzoate  of  soda  with  that  of  juice  free  from  this  pre- 
servative. 

4.  Balling  Degree. — Determine  the  Balling  degree  by  means  of  a 
Balling  hydrometer  and  record  the  temperature.     Also  determine  the 
concentration  by  a  Baume  hydrometer  and  by  an  accurate  specific- 
gravity  hydrometer  or  Westphal  balance.    Convert  Baume  and  specific- 
gravity  readings  to  the  corresponding  Balling  degree  by  means  of  Table 
XIV.    Correct  all  readings  for  temperature  by  means  of  Table  XIII. 

If  desired,  cane  sugar  and  invert  sugar  may  be  determined  by  the 
methods  given  in  the  Appendix,  page  100. 

5.  Acid. — By  means  of  a  pipette  measure  10  c.c.  of  the  sample  into  a 
500-c.c.  flask.     (With  lemon  juice  dilute  10  c.c.  to  exactly  100  c.c.,  mix 
and  take  10  c.c.  of  diluted  juice  for  titration.)     To  light-colored  juices 
add  about  100  c.c.  and  to  dark-colored  juices  about  300  c.c.  of  recently 
distilled  water  and  a  few  drops  of  phenolphthalein  indicator.    Titrate  as 
directed  on  page  98  of  Appendix  and  express  as  grams  of  citric  acid  per 
100  c.c.  of  juice  for  citrus,  pineapple  and  berry  juices;  as  of  tartaric  acid 
for  grape  juice;  and  as  of  malic  acid  for  apple  juice.     If  the  sample  is 
carbonated,  heat  to  boiling  10  c.c.  of  juice  diluted  with  distilled  water 
before  titration. 

35 


36  LABORATORY  MANUAL 

Suggestions: 

1.  Compare  the  quality  and  the  composition  of  the  commercial  juices 
with  the  fresh  juices  prepared  in  Assignment  XIII. 

2.  Carbonated  beverages  (bottled  soda  waters)  prepared  either  from 
pure  fruit  juices,  pure  fruit  syrups,  or  artificially  flavored  and  colored 
syrups  may  be  examined  in  a  similar  manner.    The  presence  of  sodium 
benzoate  and  coal-tar  colors  may  be  tested  qualitatively  as  directed  in 
the  Appendix,  page  102.     The  pressure  of  carbon  dioxide  may  be  deter- 
mined  by  shaking   the  unopened   bottle   vigorously    and   piercing  the 
crown  cap  with  a  pressure  gauge  equipped  with  a  sharp-pointed  connec- 
tion, similar  to  a  vacuum  can-tester. 


ASSIGNMENT   XII.— EXPERIMENTAL   PREPARATION   OF 

FRUIT  JUICES 

Materials. — Fifty  pounds  of  sound,  ripe,  tart  apples  or  grapes. 

Procedure : 

1.  Effect  of  Temperature  of  Pasteurization  on  Quality  and  on  Pres- 
ence of  Organisms. — Extract  the  juice  from  the  fruit  as  directed  in  As- 
signment XIII.    To  800  c.c.  of  juice  add  several  loopfuls  each  of  active 
yeast  and  of  ordinary  green  mold  (Penicillium  glaucum)  spores.     Mix 
thoroughly.     Fill  five  4-  or  8-ounce  bottles  and  seal  with  crown  caps. 
Place  one  bottle  in  a  horizontal  position  in  a  pot  and  cover  completely 
with  cold  water.    Place  in  the  pot  another  bottle  containing  water  into 
which  is  inserted  a  thermometer  through  a  rubber  stopper.    Heat  slowly 
until  the  thermometer  registers  55°C.     Maintain  this  temperature  20 
minutes  and  remove  the  bottle  of  juice.     In  a  similar  way  heat  bottle 
No.  2  to  60°C.  for  20  minutes;  No.  3  to  70°C.  for  20  minutes;  No.  4  to 
80°C.  for  20  minutes;  and  No.  5  in  boiling  water  for  20  minutes.    Store 
all  samples  4  weeks  and  examine  for  flavor  and  evidences  of  spoilage 
Repeat  this  series,  using  carbonated  juice  (see  Assignment  XII  2). 

2.  Effect  of  Carbon  Dioxide  on  Temperature  of  Pasteurization. — If 
carbonating  equipment  is  available,  carbonate  to  50  pounds  gas-pressure 
enough  juice,  inoculated  with  yeast  and  mold  as  in  Paragraph  1,  to  fill 
four  bottles.    Cap  at  once  and  heat  one  bottle  at  each  of  the  tempera- 
tures used  in  Paragraph  1  for  20  minutes.    Omit  the  boiling-water  test. 
Store  4  weeks  and  compare  with  the  samples  from  Assignment  XII  1. 

If  a  carbonating  machine  is  not  available  place  about  1,000  c.c.  of  the 
juice  in  a  large  bottle  and  cool  to  about  0°C.  (32°F.)  by  placing  the 
bottle  in  crushed  ice.  Pass  a  slow  stream  of  carbon  dioxide  from  a  Kipp 
generator  or  cylinder  of  carbon  dioxide  into  the  juice  for  20  minutes, 
stirring  occasionally.  Bottle,  cap  and  proceed  as  above. 

3.  Caps  as  a  Source  of  Mold. — Wrap  5  crown  caps  in  paper  and  heat 
in  a  steam  sterilizer  at  212°F.  for  1  hour. 

Fill  ten  4-ounce  bottles  with  juice  and  plug  with  cotton.  Heat  in  a 
steam  sterilizer  for  one  hour  at  212°F.  Allow  to  cool. 

Flame  the  necks  of  the  bottles  and  cap  five  bottles  with  sterile  caps, 
using  every  precaution  possible  against  infection  of  the  cork  discs.  Cap 
the  remaining  five  bottles  with  untreated  caps. 

Place  the  bottles  in  a  pot  of  cold  water  and  heat  to  60°C.  (140°F.) 

37 


38  LABORATORY  MANUAL  OF 

for  15  minutes.     Store  for  8  weeks  and  examine  for  evidence  of  mold 
growth. 

4.  Bottles  as  a  Source  of  Mold. — Plug  five  4-ounce  bottles  with  cotton 
and  sterilize  one  hour  in  a  steam  sterilizer  at  212  °F.    Cool. 

Sterilize  1,500  c.c.  of  juice  in  a  large  bottle  plugged  with  cotton  at 
212°F.  in  a  steam  sterilizer.  Cool.  Sterilize  10  caps  as  directed  in 
Paragraph  3. 

Flame  the  necks  of  the  sterile  bottles  and  of  the  bottle  of  juice.  Fill 
the  five  sterile  bottles  with  sterile  juice  and  seal  with  sterile  caps. 

Fill  five  rinsed  but  not  sterile  bottles  with  sterile  juice  and  seal  with 
sterile  caps. 

Pasteurize,  store  and  examine  as  in  Assignment  XII  3. 

5.  Effect  of  Temperature  and  Infusorial  Earth  on  Filtration. — Place 
100  c.c.  of  juice  in  a  folded  filter  paper  in  a  funnel  and  measure  the 
volume  of  juice  which  filters  through  in  five  minutes. 

To  100  c.c.  of  juice  add  3  grams  of  a  finely  ground  infusorial  earth, 
such  as  "Filter-eel."  Mix  thoroughly  and  determine  the  rate  of  filtration 
as  above.  Compare  the  clearness  with  that  of  untreated  filtered  juice. 

Heat  100  c.c  of  juice  to  165 °F.  with  3  grams  of  Filter-eel  and  deter- 
mine the  rate  of  filtration  and  clearness.  Note  effect,  if  any,  of  the 
Filter-eel  on  the  flavor. 

6.  Clarification  with  Finings. — Allow  3,000  c.c.  of  fresh  juice  to  stand 
overnight.    Separate  from  the  sediment  by  siphoning  or  decantation. 

A.  Egg  Albumen. — Prepare  100  c.c.  of  a  2  per  cent,  solution  of  dried 
egg  albumen  in  water  by  shaking  the  finely  ground  albumen  in  warm 
water  (not  above  110°F.).    To  100  c.c.  portions  of  the  settled  juice  in 
4-oz.  bottles  add  enough  of  the  albumen  solution  to  be  equivalent  to 
additions  of  0,  25,  50,  100  and  200  grams  per  hectoliter  (100  liters)   of 
juice.     Cap  the  bottles  and  mix  contents  thoroughly  by  shaking.     Heat 
to  165°F.   for  20  minutes.     Shake  and  set  aside  for  24  hours.     Note 
results.     If  any  of  the  bottles  are  clear,  decant  off  the  clear  juice,  filter, 
bottle,  and  pasteurize  at  165°F.     Store  and  compare  later  with  untreated 
pasteurized  juice  for  clearness  and  flavor. 

B.  Casein. — To  2  grams  of  casein  add  2  c.c.  concentrated  ammonia 
and  50  c.c.  of  water.    Boil  until  there  is  no  longer  any  odor  of  ammonia. 
Dilute  to  100  c.c.  and  use  this  casein  solution  to  repeat  clarifying  tests 
as  directed  for  egg  albumen  above. 

C.  Spanish  Clay. — To  20  grams  of  finely  ground  Spanish  clay  in  a 
mortar  add  50  c.c.  of  water.    Grind  to  a  smooth  paste.    Add  50  c.c.  more 
of  water  and  repeat  grinding.    Dilute  to  200  c.c. 

Repeat  the  clarifying  tests  as  directed  for  egg  albumen,  but  use  the 
clay  suspension  at  the  rate  of  200,  500,  1,000  and  1,500  grams  (dry 
weight)  of  clay  per  hectoliter.  The  addition  of  one  c.c.  of  the  10  per 


FRUIT  AND  VEGETABLE  PRODUCTS  39 

cent,  clay  suspension  per  100  c.c.  of  juice  corresponds  to  100  grams  of 
clay  per  hectoliter. 

7.  Comparison  of  Glass  and  Tin  Containers. — Fill  one  plain  No.  2 
tin  and  one  No.  2  lacquered  can  (completely)  with  juice,  using  berry  or 
red  grape  juice  if  available.    Heat  in  a  water  bath  to  165°F.  and  seal 
at  once.    Fill  one  No.  2  plain  tin  can  and  one  bottle  with  the  same  juice 
and  seal  without  heating.     Pasteurize  the  cans  and  bottle  of  juice  in 
water  at  165°F.  for  30  minutes.    Store  one  month  and  compare  quality 
of  juices  and  effects  on  container. 

8.  Solubility  of  Metals  in  Fruit  Juice. — Weigh  to  one-tenth  of  a 
milligram  clean  dry  pieces  of  iron,  tin,  aluminum,  copper,  zinc,  silver, 
nickel  and  monel  metal  of  approximately  the  same  surface  area.    Place 
in  individual  beakers  containing  100  c.c.  of  juice  and  boil  slowly  for  30 
minutes.     Remove  the  metals,  wash   and   dry  thoroughly   and   weigh. 
Note  the  comparative  losses  in  weight  and  calculate  the  loss  in  milli- 
grams per  square  centimeter. 


ASSIGNMENT   XIII.— PRACTICE    IN   THE   PREPARATION 

OF  FRUIT  JUICES 

Materials. — Five  to  ten  pounds  each  of  the  following  fruits  in  season: 
Apples,  grapes,  oranges,  lemons,  pomegranates,  and  loganberries  or 
blackberries. 

Procedure : 

1.  Preparation. — Remove  all  unsound  fruit  and  weigh.     Wash  thor- 
oughly.    Cut  citrus  fruits  in  half.     Separate  the  arals  of  pomegranates 
from  the  peel  and  "rag"  and  determine  the  yield  of  arals. 

2.  Crushing. — Crush  thoroughly  all  fruits  except  citrus  fruit. 

3.  Heating. — Heat  crushed  berries  and  red  grapes  in  a  jelly  kettle 
or  aluminum  pot  to  160°F.  with  constant  stirring.     Other  fruits  are  not 
heated  before  pressing. 

4.  Extraction  of  Juice. — Enclose  the  crushed  fruits  in  heavy  cloths 
and  press  in  a  small  hand-press  or  under  hydraulic  pressure.     Stir  the 
pressed  fruit  and  subject  it  to  a  second  pressing.     It  is  customary  to 
place  the  crushed  fruit  in  coarsely  woven  press-cloths  between  wooden 
racks  and  to  subject  it  to  a  pressure  of  about  400  pounds  per  square  inch 
for  at  least  30  minutes. 

Extract  the  pulp  and  juice  from  halved  citrus  fruits  by  means  of  a 
glass  cone  or  a  rotating  bronze  or  aluminum  cone.  Strain  the  juice 
through  cheese  cloth  to  separate  the  coarse  pulp.  Measure  the  volume 
of  juice  obtained  from  each  fruit  and  weigh  the  pomace.  Determine  the 
Balling  degree  and  acidity  of  juice. 

From  Table  XIV  obtain  the  corresponding  specific  gravity  of  the 
juice  and  calculate  the  yield  of  juice  by  weight.  Calculate  the  yield  of 
juice  in  percentage  and  in  gallons  per  ton  of  fresh  fruit. 

5.  Clearing. — Citrus  juices  should  be  bottled  while   cloudy.     Other 
juices  should  be  clear. 

Set  the  freshly  expressed  juice  aside  in  a  cool  place  for  24  hours. 
Separate  from  the  sediment.  Heat  to  165°F.  Cool.  Filter,  using  a 
small  amount  (1  to  3  per  cent.)  of  infusorial  earth  if  necessary. 

6.  Bottling  or  Canning. — Put  the  juice  into  clean  bottles,  filling  to 
within  about  1  inch  of  the  top,  and  seal  with  crown  caps. 

Fill  one  plain  tin  can  with  apple  juice  and  one  lacquered  can  with 
a  red  fruit  juice.  Exhaust  to  165°F.  and  seal. 

40 


41 


42  LABORATORY  MANUAL 

7.  Pasteurizing. — Pasteurize  30  minutes  at  165°F.  Chill  cans  in  cold 
water.  Store  bottles  in  a  cool,  dark  place. 

Suggestions: 

1.  Utilization  of  Pomace. — A.  Jelly  Stock:  The  pomace  of  fruits 
rich  in  pectin  (such  as  apples,  grapes  and  sour  berries)  may  be  utilized 
for  jelly  stock.  To  extract  the  pectin  mix  the  pomace  with  about  twice 
its  weight  of  water  and  boil  about  ten  minutes.  Citrus  fruits  require 
40  minutes.  Press  out  the  extract  and  strain  it  through  a  jelly  bag. 
Measure  the  volume  obtained  and  determine  its  Balling  degree  and 
acidity.  Pasteurize  in  lacquered  cans  or  bottles  for  future  use. 

B.  Dried  Pomace. — The  pomace  may  also  be  dried  and  the  yield  of 
dry  material  determined.    The  pectin  of  dried  pomace  from  apples  and 
other  jelly  fruits  may  be  extracted  for  jelly  making. 

C.  Value  for  Syrup  or  Vinegar. — From  the  yield  and  composition  of 
the  juice  obtained  in  the  preparation  of  jelly  stock  can  be  determined 
the  value  of  the  pomace  as  a  source  of  syrup  or  vinegar. 


ASSIGNMENT    XIV.— PREPARATION    OF    FRUIT    SYRUPS 

Materials. — Apples  or  grapes,  100  pounds.  Strawberries  or  other 
berries,  15  pounds.  Samples  of  commercial  fruit  syrups. 

Procedure : 

1.  Weigh  the  apples  or  grapes  carefully  and  extract  the  juice  as 
directed  in  Assignment  XIII.    Heat  to  165°F.  and  allow  to  settle.    Filter. 
Determine  the  Balling  degree,  specific  gravity  and  acid. 

2.  Concentration  in  Vacua. — Place  a  measured  volume  of  the  filtered 
juice  in  a  small  steam- jacketed  vacuum  pan.     Concentrate  rapidly  to 
65°  Balling,  corrected  to  20°C.   (68°F.),  using  highest  vacuum  attain- 
able, preferably  not  less  than  28  inches  of  mercury.    Measure  the  volume 
of  the  syrup. 

Bottle  or  can  in  lacquered  cans  and  pasteurize  at  165°F.  for  30 
minutes. 

If  a  steam-jacketed  vacuum  pan  is  not  available  the  juice  may  be 
concentrated  in  a  heavy-walled  flask  immersed  in  a  pot  of  water  at  175° 
to  180°F.  and  connected  through  a  water-cooled  condenser  to  a  vacuum 
pump.  The  flask  should  also  be  equipped  with  a  vacuum  gauge  and 
thermometer.  See  Fig.  9. 

Note  the  temperature,  vacuum  and  time  required  to  concentrate  the 
juice. 

3.  Concentration  in  Open  Pan. — Place   a  measured  volume  of  the 
filtered  juice  in  a  steam-jacketed  kettle.     Concentrate  rapidly  to  65° 
Balling,  corrected  to  20°C.  (68°F.).    Record  concentration  and  note  time 
required. 

If  a  steam-jacketed  kettle  is  not  available  concentrate  the  juice  in  an 
aluminum  or  agate-ware  kettle  over  a  flame. 

Pasteurize  in  bottles  or  in  lacquered  cans  as  directed  in  Assign- 
ment XIV  2. 

4.  Concentration  to  Prevent  Spoiling. — Concentrate  about  2,000  c.c. 
of  juice  to  75°  Balling,  corrected  to  20°C.   (68°F.).     Dilute  small  por- 
tions to  70°,  65°  and  60°  Balling,  respectively.    Place  each  sample  in  a 
bottle  and  add  a  loopful  of  yeast  and  mold  spores  to  each.     Cork  the 
bottles  and  store  for  several  weeks  at  room  temperature.     Examine  to 
determine  concentration  necessary  to  prevent  spoiling. 

5.  Neutralized  Syrup. — Add  to  a  measured  quantity  of  filtered  juice 
sufficient  precipitated  chalk   (calcium  carbonate)  to  reduce  the  acidity 
of  the  final  syrup  to  0.4  grs.  per  100  c.c.    The  expected  yield  of  syrup 
may  be  calculated  from  the  data  obtained  in  Assignment  XIV  2  or  by 

43 


44 


LABORATORY  MANUAL  OF 


formula  No.  1  on  page  45.  The  quantity  of  calcium  carbonate  required 
may  be  obtained  by  formula  No.  2  on  page  45.  Boil  the  juice  and  calcium 
carbonate  about  one  minute.  Set  aside  overnight.  Filter.  Concentrate 
to  65°  Balling,  determine  the  yield  and  pasteurize  as  in  Assignment  XIV  2. 
6.  Decolorized  Syrup. — To  a  measured  quantity  of  juice  add  enough 
precipitated  chalk  (calcium  carbonate)  to  neutralize  the  acid  completely. 
Add  3  per  cent,  by  weight  of  finely  ground  bone-black  or  1  per  cent,  of 
Eponit,  Noirit  or  other  finely  ground  vegetable  decolorizing  carbon.  Stir. 
Heat  to  boiling.  Filter.  Concentrate  in  vacua  to  65°  Balling;  determine 
the  yield  and  pasteurize  as  directed  in  Assignment  XIV  2. 


FIG.  9. — Sketch  of  laboratory  apparatus  for  vacuum  distillation.  A,  Boiling  flask > 
B,  Pot  of  water  to  heat  boiling  flask;  C,  Thermometer;  D,  Glass-condenser;  E, 
Receiving  bottle  for  distillate;  F,  Vacuum  pump;  G,  Electric  motor. 

7.  Concentration  by  Freezing. — Place  a  measured  volume  of  the  juice 
in  a  cold-storage  room  at  0°  to  10°F.  Allow  to  freeze  to  a  mixture  of 
ice  crystals  and  syrup  of  "mushy"  consistency.  Place  the  partially  frozen 
juice  in  a  perforated  centrifuge-basket  and  separate  from  the  juice  by 
centrifugal  action.  Repeat  the  freezing  and  centrifuging  at  least  three 
times  in  order  to  obtain  a  concentrated  juice  of  at  least  50°  Balling. 
Determine  the  yield  and  pasteurize  as  directed  in  Assignment  XIV  2. 

If  a  freezing  room  and  centrifuge  are  not  available  the  juice  may  be 
frozen  in  an  aluminum  or  agate-ware  pot  immersed  in  an  ice-and-salt 
mixture  or  in  an  ice-cream  freezer  and  the  syrup  separated  from  the  ice 
crystals  by  draining  through  a  fine  screen  or  cheese  cloth. 


FRUIT  AND  VEGETABLE-PRODUCTS  45 

8.  Berry  Syrup  by  Addition  of  Sugar.  —  Prepare  juice  from  a  weighed 
amount  of  berries  as  in  Assignment  XIII.     Allow  to  settle  and  filter. 
Determine  the  acidity  and  the  Balling  degree.    Add  sufficient  sugar  to 
increase  the  concentration  to  65°  Balling.     Determine  the  yield.     Pas- 
teurize as  directed  in  Assignment  XIV  2. 

9.  Comparison  of  Samples.  —  Store  all  prepared  samples  for  four  weeks 
or  longer.    Compare  carefully  with  respect  to  flavor,  color,  odor,  acidity 
and  general  quality.    Also  compare  the  experimentally  prepared  syrups 
with  commercial  syrups  if  obtainable.    Determine  the  Balling  degree  and 
acidity  of  commercial  samples. 

Suggestions: 

1.  Formula  for  Calculating  Yield  of  Syrup: 

sXbXlOO 
SXB 

G  =  yield  of  syrup  from  100  parts  of  juice  by  volume 
s  =  specific  gravity  of  juice 
S  =  specific  gravity  of  syrup 
b==  Balling  degree  of  juice 
B  =  Balling  degree  of  syrup 

2.  Formula  for  Reducing  Acidity  of  Syrup  by  Neutralization  of  Acid 
in  Juice  Before  Concentration: 

* 


S  N 

J  =c.c.  juice  used 
A  =  gms.  acid  per  100  c.c.  juice 
S  =  c.c.  syrup  obtained 

R  =  gms.  acid  to  be  retained  per  100  c.c.  syrup 
N  =  gms.  acid  neutralized  by  100  gms.  calcium  carbonate 
C  =  gms.  calcium  carbonate  required 

Theoretically  100  gms.  calcium  carbonate  (CaCO3)  will  neutralize 
134  gms.  malic  acid  (C4H0O5)  in  apple  juice  or  150  gms.  tartaric  acid 
(C4H6OC)  in  grape  juice. 

3.  Determination  of  Acidity  of  Syrups.  —  On  account  of  the  viscosity 
of  most  syrups  it  is  necessary  to  weigh  a  sample  of  the  syrup  (10  grams) 
for  titration,  rather  than  to  measure  the  volume  of  the  sample  by  means 
of  a  pipette. 

4.  Determination  of  Balling  Degree   of  Syrups.  —  If  syrup   is   very 
viscous  it  is  necessary  to  mix  100  grams  (not  100  c.c.)  of  the  syrup  with 
100  c.c.  of  distilled  water  before  making  the  Balling  test.     The  reading 
thus  obtained  must  be  multiplied  by  2. 


ASSIGNMENT  XV.— EXAMINATION  OF  COMMERCIAL 
JELLIES,  JAMS,  MARMALADES  AND  PRESERVES 

Materials. — Samples  of  the  above  products. 

Procedure : 

1.  Determine  the  net  contents  of  the  containers  by  weight. 

2.  Note  the  appearance,   color,  flavor,  odor  and   clearness   of   each 
syrup  or  jelly.    The  samples  should  be  examined  carefully  for  evidence 
of  mold  growth  and  of  fermentation. 

3.  Determine  the  Balling  degree  and  total  acid  of  the  syrup  from 
each  preserve  as  directed  in  Assignment  XIV.    Place  a  50-gram  sample 
of  jelly  or  marmalade  in  a  weighed  400-c.c.  beaker.     Add  exactly  100 
c.c.  of  water.    Heat  and  stir  until  dissolved.    If  necessary  add  water  to 
replace  that  lost  during  heating.    Cool  and  determine  the  Balling  degree 
and  acid.    Multiply  the  results  by  three. 

4.  Microscopical  Examination. — Mount  small  samples  of  the  prod- 
ucts on  a  microscope  slide.    Very  concentrated  products  and  jams  should 
be  diluted  on  the  slide  with  a  drop  of  distilled  water.    The  presence  of 
large  numbers  of  micro-organisms,  especially  mold  filaments  or  yeast 
cells,  indicate  the  use  of  partially  decomposed  raw  material. 

5.  Artificial  Color  and  Benzoate  of  Soda. — The  presence  of  artificial 
color   or   sodium   benzoate    may    be    determined    qualitatively    by    the 
methods  given  in  the  Appendix,  page  102. 

Suggestions: 

1.  Definitions — A.  Jelly. — Jelly  is  prepared  by  boiling  fruit  with  or 
without  water,  expressing  and  straining  the  juice,  adding  sugar  (sucrose) 
and  concentrating  to  such  consistency  that  gelatinization  takes  place  on 
cooling.  A  perfect  jelly  is  clear,  sparkling,  transparent  and  attractive 
in  color.  When  removed  from  the  glass  it  should  retain  its  form  and 
should  quiver,  not  flow.  It  should  not  be  syrupy,  sticky  or  gummy  and 
should  retain  the  flavor  and  aroma  of  the  original  fruit.  When  cut  it 
should  be  tender  and  yet  so  firm  that  a  sharp  edge  and  a  smooth  sparkling 
cut-surface  remain. 

B.  Marmalade. — True  marmalade  is  clear  jelly  in  which  is  suspended 
slices  of  fruit  or  peel. 

C.  Jam. — Jam  is  prepared  by  boiling  the  whole  fruit  pulp  with  sugar 
(sucrose)  without  retaining  the  shape  of  the  fruit.     It  is  concentrated 
to  a  thick  consistency  without  straining.    Government  pure-food  regula- 

46 


47 

tions  require  the  use  of  not  less  than  45  pounds  of  fruit  to  each  55  pounds 
of  sugar. 

D.  Butter. — Fruit  butter  is  prepared  by  boiling  the  strained   fruit 
pulp,  with  or  without  the  addition  of  sugar,  fruit  juice  or  spices,  to  a 
semi-solid  mass  of  homogeneous  consistency.     It  differs   from  jam  in 
being  of  a  finer  texture  and  a  higher  concentration. 

E.  Paste. — Fruit  paste  is  prepared  as  described  for  fruit  butter,  but 
is  concentrated  to  a  semi-solid  consistency  by  boiling  and  is  then  dried 
to  a  solid  consistency  resembling  candy. 

F.  Preserves. — Preserves  are  made  by  cooking  the  prepared  fruit  in 
a  sugar  (sucrose)  syrup  until  the  concentration  of  sugar  reaches  55  to  70 
per  cent.    The  fruit  should  retain  its  form,  be  crisp  rather  than  soft,  and 
should  be  permeated  with  the  syrup.    Government  pure-food  regulations 
require  that  not  less  than  45  pounds  of  fruit  be  used  for  each  55  pounds 
of  sugar. 


ASSIGNMENT  XVI.— EXPERIMENTAL  PREPARATION  OF 
JELLY  AND  MARMALADE 

Materials. — Sour  apples  15  pounds,  oranges  5  pounds,  and  lemons 
5  pounds. 

Procedure : 

1.  Preparation. — Prepare  jelly  stock  from  a  weighed  amount  of  sour 
apples  (about  15  pounds),  as  directed  in  Assignment  XVII.    Test  quali- 
tatively for  pectin  content  as  directed  in  Assignment  XVII.    If  the  juice 
is  not  rich  in  pectin,  concentrate  by  boiling  until  a  heavy  pectin  precipi- 
tate is  obtained  by  the  alcohol  test.    Record  the  yield,  acidity  and  Ball- 
ing degree. 

2.  Effect  of  Pectin  Concentration. — A.  Dissolve  185  grams  of  sugar 
in  100  c.c.  of  the  prepared  juice.    Heat  to  boiling  for  one  minute.    Skim 
and  pour  into  a  glass. 

B.  To  50  c.c.  of  the  juice  add  50  c.c.  of  water.     Add  185  grams  of 
sugar  and  treat  as  in  A. 

C.  To  25  c.c.  of  the  juice  add  75  c.c.  of  water,  185  grams  of  sugar 
and  proceed  as  in  A. 

Compare  consistencies  of  the  samples  after  48  hours. 

3.  Effect  of  Acidity. — A.  If  the  acidity  of  the  juice  is  less  than  1  per 
cent.,  increase  the  acidity  of  100  c.c.  to  1  per  cent,  by  the  addition  of 
citric  acid.    Add  185  grams  of  sugar,  dissolve,  and  heat  to  boiling  for  one 
minute.    Skim  and  pour  into  a  glass. 

B.  Repeat  A,  increasing  the  acidity  to  2  per  cent. 

C.  Repeat  A,  increasing  the  acidity  to  5  per  cent. 

D.  Reduce  the  acidity  of  100  c.c.  of  juice  to  0.2  per  cent,  by  the 
addition  of  the  calculated  amount  of  sodium  carbonate  (Na2CO3).    One 
gram  of  Na2C03  will  neutralize  1.21  grams  citric  and  1.26  grams  malic 
acid.     Add  185  grams  of  sugar,  boil  one  minute;  skim  and  pour  into 
a  glass. 

Compare  the  consistencies  and  flavors  of  samples  after  48  hours. 

4.  Effect  of  Sugar  Concentration. — To  100  c.c.  portions  of  the  juice 
add  50,  150,  200  and  300  grams  of  sugar,  respectively.     Dissolve  the 
sugar,  boil  each  sample  one  minute,  skim  and  pour  into  glasses. 

Compare  the  consistencies   and   flavors  after  48  hours.     Note  the 
presence  or  absence  of  sugar  crystals. 

48 


FRUIT  AND  VEGETABLE  PRODUCTS  49 

5.  Effect  of  Temperature. — Dissolve  in  each  of  three  100-c.c.  portions 
of  juice  185  grams  of  sugar.     Heat  one  lot  to  boiling  one  minute,  the 
second  lot  to  165°F.  one  minute,  and  the  third  lot  in  an  autoclave  at 
10  pounds  steam  pressure  (240°F.)  five  minutes. 

Compare  for  color,  flavor  and  consistency  after  48  hours. 

6.  Comparison  of  Jelling-point  Tests. — To  each  of  four  100-c.c.  lots 
of  the  juice  add  100  grams  of  sugar.    Boil  in  an  open  pot  with  a  ther- 
mometer inserted  in  the  boiling  liquid.    Remove  lot  1  when  the  heating 
point  reaches  216°F.;  lot  2  at  218°F.;  lot  3  at  221°F.,  and  lot  4  at 
225°F.    Also  allow  some  of  the  hot  liquid  to  drip  from  a  spoon  and  note 
whether  the  drops  congeal  or  not,  and  determine  the  Balling  degree  of 
each  lot  as  soon  as  removed  from  the  fire  (making  the  necessary  tem- 
perature corrections). 

Compare  the  flavors,  colors  and  textures  after  48  hours. 

7.  Jelly  from  Dried  Apple  Waste. — To  100  grams  of  dried  peels  and 
cores  of  apples   (canning  refuse)   or  of  dried  pomace  from  apple-juice 
manufacture  add  500  c.c.  of  water.    Bring  to  the  boiling  point  and  set 
aside  overnight.    Boil  about  20  minutes,  press  and  filter. 

Test  for  pectin  and  if  necessary  concentrate  until  a  fairly  heavy  test 
is  given. 

Add  an  equal  quantity  of  berry  juice,  such  as  strawberry  juice  or 
commercial  grape  juice,  and  sugar  in  the  proportion  of  75  grams  per 
100  c.c.  of  mixed  juice  and  concentrate  to  a  boiling  point  of  221  °F. 
Pour  into  glasses  and  store  for  subsequent  examination. 

8.  Citrus  Fruit  Marmalade — A.   Preparation. — Prepare   jelly    stock 
from  a  weighed  amount  of  citrus  fruit,  about  5  pounds  each  of  oranges 
and  lemons,  as  directed  in  Assignment  XVII.     Test  qualitatively  for 
pectin  content  and,  if  a  heavy  test  is  not  secured,  concentrate  by  boiling. 
Record  the  yield,  acidity  and  Balling  degree. 

B.  Effect  of  Preliminary  Boiling  of  Peel. — To  200  c.c.  of  the  juice 
add  30  grams  of  shredded  peel  and  150  grams  of  sugar.     Boil  until  a 
thermometer  in  the  liquid  registers  221  °F.  and  pour  into  a  glass. 

To  30  grams  of  the  shredded  peel  add  about  300  c.c.  of  water.  Boil 
until  the  shreds  are  tender.  Drain  off  and  discard  the  water.  To  the 
drained  peel  add  200  c.c.  of  juice  and  150  grams  of  sugar.  Heat  to 
221  °F.  Pour  into  a  glass. 

Compare  the  texture  of  the  peel  in  the  two  lots  after  48  hours. 
Measure  the  yield  of  finished  product. 

C.  Effect  of  Cooling  before  Pouring. — Prepare  a  sample  of  marma- 
lade as  directed  in  B,  using  the  boiled  peel,  but  allow  the  product  to  cool 
in  the  pot  with  occasional  stirring  until  it  shows  slight  signs  of  jelling. 
Pour  it  into  a  glass  and  after  cooling  note  whether  the  shreds  are  more 
evenly  distributed  in  the  product  than  in  B. 


50  LABORATORY  MANUAL 

D.  Effect  of  Proportion  of  Peel. — To  100-c.c.  lots  of  the  juice  add 
5,  10,  20  and  30  grams,  respectively,  of  thinly  sliced  boiled  peel  and  100 
grams  of  sugar.  Concentrate  each  lot  until  a  boiling  point  of  221  °F. 
is  reached.  Pour  into  glasses.  Compare  as  to  texture,  appearance  and 
general  quality  after  48  hours. 


ASSIGNMENT  XVII.— PRACTICE  IN  THE  PREPARATION 
OF  JELLY  AND  MARMALADE 

Materials. — Any  fruit  in  season  suitable  for  jelly  making. 

Procedure : 

1.  Condition  of  Fruit. — Fruit  for  jelly  should  be  sound  and  clean  and 
not  thoroughly  ripe,  as  under-ripe  fruit  is  richest  both  in  pectin  and 
in  acid. 

2.  Extraction  of  Pectin. — The  pectin  must  be  released  from  the  fruit 
tissues  by  boiling.    Very  juicy  fruits  such  as  berries  are  merely  crushed 
and  boiled  about  5  minutes  without  the  addition  of  water.     Hard  fruits 
such  as  quinces  or  apples  are  cut  into  small  pieces,  barely  covered  with 
water  and  boiled  10  or  15  minutes  till  tender.     Citrus  fruits  are  sliced 
without  peeling  into  thin  pieces,  covered  with  water  and  boiled  about 
one  hour. 

3.  Pressing  and  Clearing. — With  large  quantities,  the  boiled  fruit  is 
pressed  as  described  under  Fruit  Juices.    The  juice  is  allowed  to  settle 
overnight  and  the  settled  juice  filtered  through  a  felt  jelly-bag.     Small 
quantities  of  boiled  fruit  are  generally  placed  directly  in  a  muslin  jelly- 
bag  and  the  clear  juice  allowed  to  drain  through.    The  last  of  the  juice 
may  be  squeezed  out,  but  it  will  be  cloudy.     The  drained  or  pressed 
pulp  of  fruits  rich  in  pectin  may  be  boiled  a  second  time  with  water 
and  drained  or  pressed. 

4.  Orange  Peel  for  Marmalade. — If  equal  quantities  of  oranges  and 
lemons  are  used  for  the  marmalade  stock,  only  one  orange  in  four  need 
be  peeled.    Remove  the  orange  peeling  by  quarters  and  cut  into  very  thin 
slices,  not  more  than  1/32  of  an  inch  thick.    Boil  the  sliced  peel  in  water 
until  tender.     Drain  and  discard  the  water. 

5.  Testing  for  Pectin. — Mix  in  a  glass  equal  quantities  of  juice  and 
95  per  cent,  grain  alcohol.     One  spoonful  or  about  10  c.c.  of  each  is 
sufficient.    The  character  and  amount  of  precipitate  indicate  the  relative 
concentration  of  pectin  as  follows: 

Juice  rich  in  pectin  =  bulky,  gelatinous,  almost  solid  mass  of  pectin. 
Juice  moderately  rich  in  pectin  =  a  few  large  pieces  of  gelatinous 
precipitate. 

Juice  poor  in  pectin  =.  small  amount  of  flaky  sediment. 

6.  Testing  for  Acid. — The  acidity  of  the  jelly  stock  may  be  deter- 
mined as  described  on  page  98.     An  acid  content  of  0.5  to  1.0  per  cent. 

51 


52 


LABORATORY  MANUAL  OF 


FRUIT  AND  VEGETABLE  PRODUCTS  53 

is  satisfactory.     Juices  with  a  distinctly  tart  taste  need  not  be  tested 
for  acid. 

7.  Proportion  of  Sugar  and  Juice. — The  amount  of  sugar  which  may 
be  added  to  the  juice  is  directly  proportional  to  the  concentration  of 
pectin  in  the  juice,  as  follows: 

To  one  cup  of  juice  rich  in  pectin  add  1  to  l1/^  cups  of  sugar. 
To  one  cup  of  juice  moderately  rich  in  pectin  add  %  to  1  cup  of  sugar. 
To  one  cup  of  juice  fairly  rich  in  pectin  add  y>  to  %  cup  of  sugar. 
Juices  poor  in  pectin  should  be  concentrated  until   a  satisfactory 
pectin  test  is  obtained  before  addition  of  sugar. 

8.  Determination  of  Jelling  Point. — The  proper  proportion  of  sugar 
and  juice  is  boiled  rapidly  until  the  mixture  reaches  a  concentration  of 
65°  to  68°  Balling  (cold  test).    The  jelling  point  may  be  determined  in 
the  following  ways,  the  thermometer  test  being  the  simplest  and  most 
reliable : 

A.  Sheeting  Test. — Dip  a  spoon  or  paddle  in  the  boiling  jelly.     Hold 
the  spoon  in  the  air  and  allow  the  jelly  to  drip  from  it.    If  the  drops  are 
syrupy  the  jelly  is  not  sufficiently  concentrated,  but  if  the  jelly  congeals 
or  drops  in  flakes  the  jelling  point  has  been  reached. 

B.  Boiling-point  Test. — Place  a  thermometer  in  the  jelly  during  con- 
centration.   When  the  jelly  boils  at  221  °F.,  equivalent  to  65°  Balling, 
the  jelling  point  is  reached. 

C.  Balling  Test. — Pour  a  sample  of  the  boiling  jelly  in  a  hydrometer 
cylinder  and  determine  Balling  degree.    At  the  jelling  point  the  Balling 
degree  of  the  hot  jelly  should  be  57°  to  58°,  equal  to  65°  when  cold. 

9.  Sealing,    Pasteurizing     and    Storage. — The     hot     finished     jelly, 
skimmed  to  insure  clearness,  is  poured  into  glasses  and  allowed  to  cool 
and  solidify.    The  surface  of  the  jelly  is  then  covered  with  a  layer  of 
hot  melted  paraffine,  which  sterilizes  the  surface  of  the  jelly  and  solidi- 
fies to  form  a  seal  about  %  inch  thick. 

Jelly  may  also  be  sealed  in  small  fruit-jars  with  caps  and  rubber 
gaskets  or  in  lacquered  cans.  This  is  necessary  where  the  jelly  is  to  be 
pasteurized  at  180°F.  for  30  minutes  in  the  case  of  soft  jellies  that  are 
below  65°  Balling,  and  especially  if  to  .be  kept  in  hot  climates. 


54 


LABORATORY  MANUAL 


Suggestions: 

1.  Suitability  of  Fruits  for  Jelly: 


Rich  in  Pectin  and 

Medium  in  Acid  and 

Rich  in  Pectin  and 

Poor  in   Acid  and 

Acid 

Pectin 

Low  in  Acid 

Pectin 

Jell  readily 

Jell  if  carefully  handled 

Add  acid  fruit 

Blend    with    fruit 
from  Column  1 

Sour  apples 

Ripe  apples 

Guavas 

Apricots 

Crab  apples 

Blackberries 

Feijoas 

Peaches 

Currants 

Oranges 

Figs 

Pears 

Loganberries 

Grape  Fruit 

Pie  melons 

Raspberries 

Cranberries 

Sweet  plums 

Strawberries 

Lemons 

Quinces 

Sour  plums 

Sour  cherries 

Eastern  grapes 

California  grapes 

2.  Common  Difficulties  in  Jelly-making,  with  Cause  or  Prevention. — 

A.  Soft  or  Syrupy  Jelly. — Too  much  sugar  for  amount  of  pectin  or 
insufficient  boiling;  add  more  juice  or  pectin  and  heat  to  221  °F. 

B.  Tough  Jelly. — Too  little  sugar  for  amount  of  pectin;  add  more 
sugar. 

C.  Gummy  Jelly. — Too  prolonged  boiling  or  over-cooking;  boil  rap- 
idly and  stop  at  221  °F. 

D.  Cloudy  Jelly. — Juice  not  strained;  jelly  not  skimmed  or  partly 
congealed  before  filling  into  glasses;  use  clear  juice,  skim  jelly  and  pour 
hot  into  glasses. 

E.  Crystals. — Sugar  crystals  due  to  lack  of  thorough  stirring  and 
dissolving  or  too  much  sugar  added  or  jelly  too  concentrated.    In  grape 
jelly  the  harmless  cream  of  tartar  crystals  may  occur. 

F.  Moldy  Jelly. — Paraffine  not  hot  when  poured  or  caps  not  steri- 
lized or  seal  not  tight.     Use  thicker  layer  of  hot  melted  paraffine  or 
sterilized  covers. 

G.  Fermented  Jelly. — Not  concentrated  to  65°  Balling.     Add  more 
sugar,  heat  to  221°F.,  or  pasteurize  in  sealed  jars. 


ASSIGNMENT  XVIIL— -EXPERIMENTAL  PREPARATION 
OF  PECTIN  AND  JELLY  STOCK 

Materials. — Apples  10  pounds,  or  oranges  and  lemons  5  pounds  each. 
Cull  fruits  may  be  used.  Commercial  powdered  pectin  and  concentrated 
pectin  solution. 

Procedure : 

1.  Preparation  of  Juice. — Prepare  jelly  stock  from  apples  or  equal 
weights  of  lemons  and  oranges  as  directed  in  Assignment  XVII.     Test 
qualitatively  for  pectin  content.    If  the  juice  is  not  rich  in  pectin,  con- 
centrate by  boiling.     Determine  the  yield,  acidity  and  Balling  degree. 

2.  Canned  Jelly  Stock. — To  100  c.c.  of  the  juice  add  100  grams  of 
sugar  and  concentrate  to  a  boiling  point  of  221  °F.     Pour  into  a  glass, 
seal  and  store  for  future  reference. 

Fill  to  overflowing  with  the  boiling  juice  one  lacquered  can  and  one 
plain  tin  can.  Seal  at  once  and  invert  to  cool.  Store  at  least  one  month. 
Open  cans  and  note  action  of  juice  on  containers.  Prepare  jelly  from 
each  sample  as  directed  above  and  compare  the  quality  with  that  of 
jelly  made  from  the  fresh  fruit. 

3.  Preparation  and  Use  of  Concentrated  Pectin  Solution. — Determine 
the  acidity  and  Balling  degree  of  a  sample  of  commercial  concentrated 
pectin  solution.    Concentrate  in  vacuo  500  c.c.  of  the  jelly  stock  to  the 
same  Balling  degree  as  the  commercial  pectin  solution.     Compare  the 
pectin  content  of  each  of  the  two  products  qualitatively  after  diluting 
one  part  of  the  sample  with  four  parts  of  water. 

Pasteurize  the  concentrated  pectin  solution  in  a  bottle  at  175°F.  for 
30  minutes.  Store  1  month.  Dilute  part  of  the  sample  to  the  concen- 
tration of  the  original  juice.  To  100  c.c.  of  the  diluted  solution  add 
100  grams  of  sugar  and  heat  to  221  °F.  Compare  witli  the  jellies  made 
from  canned  jelly  stock  and  fresh  juice  in  Assignment  XVIII  2. 

To  100  c.c.  of  strawberry  juice,  or  other  juice  poor  in  pectin,  add 
enough  of  the  concentrated  pectin  solution  to  give  a  strong  pectin  test 
and  record  the  amount  used.  Prepare  jelly  as  directed  above.  For 
comparison  add  to  100  c.c.  of  the  juice  poor  in  pectin  enough  concen- 
trated commercial  pectin  solution  to  give  a  strong  pectin  test  and  prepare 
jelly  from  the  mixture.  Compare  amounts  of  the  two  pectin  solutions 
required  to  give  similar  qualitative  pectin  tests  and  compare  the  jellies 
obtained  as  to  quality. 

55 


56  LABORATORY  MANUAL 

4.  Preparation  of  Powdered  Pectin. — Concentrate  1,000  c.c.  of  the 
jelly  stock  in  vacuo  to  about  45°  to  50°  Balling.  Cool,  and  add  the 
concentrated  juice  slowly  with  stirring  to  twice  its  volume  of  95  per  cent, 
ethyl  (grain)  alcohol.  Separate  the  alcohol  from  the  pectin  by  draining 
through  a  muslin  cloth  and  pressing.  Dry  at  room  temperature  on  a 
screen.  Dissolve  the  dried  pectin  in  a  small  amount  (about  150  c.c.) 
of  water  and  strain  through  a  cloth.  Add  the  pectin  solution  to  twice 
its  volume  of  ethyl  alcohol  and  separate  the  precipitate  by  straining 
through  muslin.  Dry  at  a  temperature  of  120°  to  130°F.  and  weigh. 
Grind  in  a  mortar  to  a  powder.  Store  in  a  corked  bottle. 

Dissolve  0.5,  1  and  2  grams,  respectively,  in  100-c.c.  lots  of  juice 
poor  in  pectin.  Add  100  grams  of  sugar  to  each.  Concentrate  by  boiling 
to  221  °F.  Pour  into  glasses  and  compare  the  samples  48  hours  later  as 
to  consistency. 

Suggestions. — The  alcoholic  liquid  from  the  pectin  precipitation 
may  be  distilled  to  recover  the  alcohol,  the  alcohol  content  of  the  dis- 
tillate determined  and  the  loss  of  alcohol  ascertained. 


ASSIGNMENT    XIX.— PRACTICE    IN    THE    PREPARATION 
OF  JAM,  BUTTER  AND  PASTE 

Materials. — Apples  10  pounds,  peaches  or  apricots  5  pounds,  berries 
5  pounds  and  pears  5  pounds.  Fruits  for  the  products  above  mentioned 
should  be  thoroughly  ripe. 

Procedure : 

1.  Jams — A.   Preparation. — Weigh   and   wash  the   fruit  thoroughly. 
Do  not  use  apples.     Peel  and  slice  peaches  and  pears.     Pit  and  slice 
apricots.    Wash  and  stem  berries.    Firm  fruits  such  as  pears  should  be 
boiled  until  soft  with  a  small  amount  of  water  before  adding  sugar. 

B.  Addition  of  Sugar. — To  sour  fruits  add  an  equal  weight  and  to 
sweet  fruits  three-fourths  their  weight  of  sugar. 

C.  Concentration. — Heat  with  constant  stirring  to  a  boiling  point  of 
218°  to  221  °F.,  or  until  the  desired  consistency  is  reached.    Seal  while 
boiling  hot  in  jars  or  glasses.    Record  the  yield. 

2.  Butters — A.  Preparation  of  Pulp. — Weigh,  peel  and  slice  apples, 
pears  or  peaches.     Boil  with  a  small  amount  of  water  until  soft.     Pass 
through  a  fine  screen. 

B.  Addition  of  Sugar  or  Fruit  Juice. — Butters  are  made  either  with 
sugar  or  fruit  juice  added  to  pulp.     If  the  former  is  used,  add  three- 
fourths  pound  of  sugar  per  pound  of  pulp;  if  the  latter,  add  3  pints  of 
apple  juice  or  grape  juice  per  pound  of  pulp. 

C.  Addition  of  Spices. — Cinnamon  and  cloves  are  usually  added  in 
the  proportion  of  one  level  teaspoonful  of  each  of  the  ground  spices  per 
3  pounds  of  pulp  or  one  gram  of  each  per  1,000  grams  of  pulp.    These 
are  added  near  the  completion  of  the  boiling  process. 

D.  Lemon  juice  is  added  to  pear  pulp  in  the  proportion  of  three- 
fourths  of  a  pint  per  10  pounds  of  pulp  or  50  c.c.  per  1,000  grams  of  pulp. 

E.  Concentration. — Concentrate  the  pulp  and   sugar  or  juice  to   a 
very  thick  consistency  (222°  to  225°F.).    Determine  the  yield  and  seal 
while  hot  in  fruit  jars  or  cans. 

3.  Paste. — Use  pears,  peaches,  apricots  or  berries.    Prepare  the  fresh 
fruit  as  described  for  butters.     Add  to  the  screened  pulp  three- fourths 
its  weight  of  sugar.    Concentrate  to  a  boiling  point  of  222°F.     Spread 
in  a  layer  about  l/2  inch  thick  in  a  buttered  or  greased  pan.     Dry  to  a 
solid  consistency  at  120°  to  160°F.  in  an  air-blast  dehydrater  or  in  a 

57 


58  LABORATORY  MANUAL 

glass-covered  dish  in  the  sun.    Cool.    Cut  into  square  blocks.     Dip  in 
powdered  sugar  and  determine  the  yield. 

Suggestions. — Commercial  pectin  or  apple  juice  rich  in  pectin  is 
often  added  to  fruit  jam  to  thicken  its  consistency  or  to  cheapen  the 
product. 


ASSIGNMENT    XX.— EXPERIMENTAL    PREPARATION    OF 
FRUIT  PRESERVES 

Materials. — Strawberries  5  pounds,  and  cherries,  oranges  or  slightly 
unripe  figs  3  pounds.  If  fresh  strawberries  are  not  in  season  it  is  usually 
possible  to  obtain  cold-storage  strawberries. 

Procedure: 

1.  Effect  of  Preliminary  Cooking. — Use  fresh  whole  figs  or  the  white 
flesh  of  watermelon  cut  in  small  cubes,  or  orange  peel  cut  in  quarters. 

A.  To  1  pound  (454  grams)  of  the  fruit,  add  1  pound.  (454  grams) 
of  sugar  and  %  pint  (about  240  c.c.)  of  water,  boil  to  221  °F.  and  allow 
to  cool. 

B.  To  1  pound  (454  grams)  of  the  fresh  fruit,  add  2  pints  (about  950 
c.c.)  of  water  and  boil  until  tender.    This  will  be  45  to  50  minutes  for 
orange  peel  and  20  to  25  minutes  for  figs  or  melon.    Discard  the  water. 
To  the  cooked  fruit  add  1  pound  (454  grams)  of  sugar  and  %  pint  (about 
240  c.c.)  of  water.    Heat  slowly  to  221  °F.    Allow  to  cool  and  compare 
the  texture  with  that  of  sample  A. 

2.  Effect  of  Method  of  C-oncentration. — A.  Place  1  pound  of  hulled 
washed  strawberries  in  an  open  kettle.    Add  1  pound  of  sugar.    Heat  to 
221  °F.  and  allow  to  cool. 

B.  Place  equal  weights  of  berries  and  sugar  in  a  large  flask  connected 
to  a  condenser  and  vacuum  pump.     Place  the  flask  in  water  at  185°F. 
and  concentrate  under  at  least  26  inches  vacuum  until  the  syrup  tests 
65°  Balling   (corrected  for  temperature).     Allow  to  cool  and  compare 
with  A  and  C. 

C.  To  1  pound  of  berries  add  1  pound  of  sugar.    Heat  slowly  to  boil- 
ing.   Boil  3  minutes.    Allow  to  stand  with  occasional  stirring  for  about 
12  hours  to  permit  the  berries  to  absorb  the  syrup.     Heat  to  185°F., 
pack  hot  into  a  jar;  seal;  pasteurize  20  minutes  at  185°F.  and  invert 
to  cool.    Compare  with  A  and  B. 

D.  To  1  pound  of  berries  add  1  pound  of  sugar.    Boil  3  minutes  and 
place  in  a  shallow  dish  in  the  sun  or  in  a  dehydrater  at  120°F.  until 
syrup  reaches  65°  Balling.    Compare  witli  A,  B  and  C. 

Suggestions. — If  fresh  fruits  are  not  in  season  dried  figs,  peaches 
or  pears  may  be  soaked  in  water  and  used  for  this  assignment. 


59 


ASSIGNMENT    XXL— PRACTICE    IN   THE    PREPARATION 
OF  FRUIT  PRESERVES 

Materials. — Five  pounds  each  of  such  fruits  as  peaches,  pears,  straw- 
berries, pineapple,  watermelon  rind,  kumquats,  cherries,  apricots  and 
firm  ripe  figs. 

Procedure : 

1.  Preparation. — Weigh   the   fruit   before   and   after   preparation   as 
follows: 

A.  Freestone  peaches — peel,  halve,  pit. 

B.  Cling-stone  peaches — peel,  but  need  not  pit. 

C.  Small  pears — peel  and  use  whole. 

D.  Large  pears — peel,  halve,  core. 

E.  Quinces — peel,  quarter  and  core. 

F.  Cherries — stem  and  pit. 

G.  Apricots — halve  and  pit. 

H.  Small  plums — puncture  skins  thoroughly. 

7.  Kumquats — slit  and  seed. 

J.  Pineapple — peel,  core  and  slice. 

K.  Watermelon — remove  red  flesh  and  green  skin. 

2.  Preliminary  Boiling. — Boil  watermelon  rind  and  fruits,  such  as 
figs,  peaches,  pears,  kumquats  and  cherries,  in  water  until  tender.     Do 
not  boil  soft  fruits,  such  as  berries  and  very  ripe  apricots  or  free-stone 
peaches. 

3.  Addition  of  Sugar. — To  each  pound  of  firm  varieties  of  fruit  add 
1  pound  of  sugar  and  1  quart  of  water.    To  berries  and  very  ripe  soft 
fruit  add  sugar  only.    Heat  firm  fruits  in  an  open  kettle  to  a  temperature 
of  221  °F. ;  boil  berries  with  gentle  stirring  3  to  4  minutes  only.     Allow 
to  cool  in  an  open  vessel,  stirring  frequently  during  cooling.     Set  aside 
for  24  hours  to  allow  the  fruit  to  absorb  the  syrup. 

4.  Packing  and  Pasteurizing. — Pack  the   fruit  carefully   into   glass 
jars.     Heat  the  syrup  from  the  fruit  to  boiling  and  fill  the  jars.     Seal 
the  jars  and  pasteurize  for  30  minutes  in  water  at  185°F. 

5.  Spiced  Preserves. — Prepare  firm  fruits  as  directed  in  Assignment 
XXI  1  and  2.     Berries  are  not  suitable  for  spiced  preserves.     Prepare  a 
syrup  consisting  of: 

60 


FRUIT  AND  VEGETABLE  PRODUCTS  61 

Sugar 1,400  grams 

Vinegar 475  c.c. 

Water 475  c.c. 

Ginger  root 7  grams 

Whole  cloves 10  grams 

Stick  cinnamon 15  grams 

Heat  the  fruit  to  boiling  in  this  syrup  and  allow  to  stand  overnight. 
Add  sugar  sufficient  to  increase  the  Balling  degree  of  the  syrup  to  60°. 
Heat  the  fruit  and  syrup  to  boiling.  Pack  hot  into  jars  and  seal.  No 
further  treatment  is  necessary. 

6.  Maraschino  Cherries. — Store  large  Royal  Anne  cherries  for  at  least 
two  weeks  in  sealed  glass-top  fruit-jars  in  a  0.3  per  cent,  solution  of 
sulphurous  acid  or  in  a  0.5  per  cent,  solution  of  sodium  metabisulphite. 

Stem  and  pit  the  cherries.  Allow  to  stand  in  water  overnight.  Boil 
in  repeated  changes  of  water  until  the  fruit  is  tender  and  free  of  sul- 
phurous acid  taste. 

Prepare  a  syrup  of  30°  Balling  with  confectioners'  gluecose  or  white 
"Karo"  syrup  and  water.  Color  the  syrup  to  the  desired  depth  and  tint 
by  the  addition  of  small  amounts  of  the  permissible  coal-tar  dyes, 
Amaranth  and  Ponceau-3-R.  Heat  the  fruit  to  boiling  in  this  syrup 
and  set  aside  for  24  hours.  Increase  the  Balling  degree  progressively 
at  24-hour  intervals  to  35°,  40°,  45°,  50°  and  55°  Balling  by  addition  of 
cane-sugar,  boiling  the  fruit  and  syrup  for  about  three  minutes  after 
each  increase.  Add  a  very  small  amount  of  bitter-almond  or  "wild 
cherry"  extract  to  the  syrup  of  55°  Balling,  heat  to  boiling  and  pack 
into  glass-jars  or  lacquered-cans.  Seal  and  sterilize  the  cans  in  boiling 
water  for  10  minutes  and  the  jars  in  water  at  185°F.  for  20  minutes. 
A  more  attractive  product  is  obtained  if  the  cherries  are  packed  in 
freshly  prepared  cane-sugar  syrup  of  55°  Balling  flavored  with  bitter- 
almond  oil. 


ASSIGNMENT   XXII.— PRACTICE  IN   THE   PREPARATION 
OF  CANDIED  FRUITS 

Materials. — Apricots,  cherries,  figs,  jujubes,  oranges,  kumquats, 
small  Seckel  pears  or  canning  peaches.  Most  fruits  for  candying  should 
be  hard  ripe. 

Procedure: 

1.  Preliminary  Treatment. — Take  a  weighed  quantity  of  the  fruit. 
Jujubes  are  first  dipped  in  boiling  1  per  cent,  sodium  hydroxide  (NaOH) 
solution  for  about  ^  minute  and  rinsed  in  water  to  remove  the  waxy 
coating  on  the  skin  and  to  render  the  skin  permeable  to  the  syrup.     Some 
whole  fruits  such  as  apricots  should  be  punctured  thoroughly  with  a  fork. 
Cherries  are  pitted  and  stemmed.    Peaches  are  peeled,  pitted  and  halved. 
The  pits  are  removed  from  large  apricots  without  cutting  in  half.    Use 
only  the  peel  of  oranges.    The  skins  of  kumquats  are  cut  longitudinally 
and  the  seeds  are  removed. 

Cook  the  fruit  in  water  until  tender,  but  not  "mushy." 

2.  Impregnation  with  Syrup. — Prepare  a  glucose  syrup  of  30°  Balling 
from  glucose  syrup  and  water.    Place  the  fruit  in  this  and  heat  to  boiling. 
Set  aside  for  24  to  48  hours. 

Pour  off  the  syrup.  Add  cane-sugar  to  increase  to  40°  Balling.  Place 
the  fruit  in  the  syrup.  Heat  to  boiling.  Set  aside  for  48  hours. 

Increase  tlie  syrup  progressively  at  48-hour  intervals  to  50°,  60°  and 
70°  Balling  by  the  addition  of  cane-sugar.  Heat  the  syrup  and  fruit 
to  boiling  after  each  increase. 

The  syrup  used  for  cherries  must  be  artificially  colored  to  give  the 
tint  commonly  seen  in  candied  cherries.  Equal  proportions  of  the  per- 
missible aniline  colors  Ponceau-3-R  and  Amaranth  are  used.  These  are 
added  when  the  first  syrup  is  prepared.  Bitter-almond  flavor  is  added 
to  the  final  syrup  for  cherries. 

3.  Drying  and  "Glaceing." — Remove  the  fruit  from  the  heavy  syrup. 
Drain  well  on  screen  trays.     Dry  the  surface  of  the  fruit  at  not  over 
130°F.     Weigh.     Part  of  this  fruit  may  be  packed  in  boxes  without 
further  treatment.    Reserve  the  remainder  for  glaceing. 

Prepare  a  concentrated  sugar-solution  containing  60  grams  of  sugar 
and  25  grams  of  glucose-syrup  per  15  c.c.  of  water.  Boil  and  allow  to 
cool  to  about  200°F.  Dip  the  remainder  of  the  fruit  in  this  very  heavy 
syrup.  Drain  and  dry  in  the  open  air  at  not  above  110°F. 

62 


FRUIT  AND  VEGETABLE  PRODUCTS  63 

Weigh  the  finished  product.     Compare  the  appearance  of  the  glace 
and  plain  samples. 

Suggestions : 

1.  If  fresh  fruits  are  unavailable,  canned  fruits  may  be  substituted. 

2.  Apples,  berries  and  very  ripe  fruits  of  any  kind  are  unsuitable  for 
candying  because  they  disintegrate  during  processing. 

3.  Cherries  are  usually  prepared  for  candying  as  described  in  Assign- 
ment XXI-6. 


ASSIGNMENT   XXIII.— EXAMINATION    OF    COMMERCIAL 
DRIED  FRUITS  AND   VEGETABLES 

Materials. — Samples  of  various  size-grades  of  sun-dried  fruits,  such 
as  peaches,  pears,  apricots,  prunes  and  raisins.  Samples  of  dehydrated 
fruits,  such  as  prunes,  apples,  berries,  peaches,  pears,  etc.  Samples  of  de- 
hydrated vegetables,  such  as  spinach,  corn,  string  beans,  soup  vegetables 
and  of  pumpkin  flour. 

Procedure : 

1.  General  Examination. — A.  Appearance. — Note  the  shade  and  uni- 
formity of  color,  comparing  with  the  natural  color  of  the  fresh  product. 
In  dried  whole  fruits,  note  the  appearance  of  the  interior  of  each.    Note 
differences  in  color  between  sun-dried  and  dehydrated  fruits.     Examine 
carefully  for  dust,  dirt,  straw  and  evidence  of  carelessness  in  peeling 
or  washing. 

B.  Flavor. — Note  the  flavor  of  each  kind  of  fruit.     Taste  for  evidence 
of  sulphurous  acid  or  caramelization  of  sugar. 

C.  Evidence  of  Spoiling. — Examine  for  evidences  of  insect  infestation. 
The  common  insects  which  may  be  found  in  dried  fruits  or  vegetables 
are,  in  order  of  their  importance: 

(a)   Indian-Meal  Moth  (Plodia  interpunctella). 
(6)   Dried-Fruit  Beetle  (Carpophilus  hemipterus). 

(c)  Grain  Beetle  (Silvanus  surinamensis). 

(d)  Dried-Fruit  Mite  (Carpoglyphus  passularum). 
Examine    for   evidence   of   micro-biological    decomposition,    namely, 

mold,  alcoholic  fermentation  or  bacterial  growth.  A  small  portion  of 
the  sample  may  be  ground  with  a  little  water  in  a  mortar  and  a  drop 
of  the  mixture  placed  on  a  glass  slide  and  examined  under  the  high  power 
of  the  microscope.  Do  not  confuse  efflorescence  of  sugar  on  the  surface 
of  fruits  with  white  mold. 

2.  Grades. — Determine  the  size  grades  of  dried  fruits  by  reference 
to  Table  X. 

3.  Chemical  Examination. — A.  Determination  of  Moisture. — Grind  a 
representative  sample  of  not  less  than  1  pound  of  fruit,  free  from  pits, 
or  ^2  pound  of  vegetable,  through  a  fine  food-chopper.     Determine  the 
moisture  by  the  official  method  as  given  on  page  102.    Moisture  in  dried 
apples  may  be  determined  by  drying  10  gramss  of  the  minced  sample  in  a 

64 


FRUIT  AND  VEGETABLE  PRODUCTS  65 

water-oven  for  exactly  4  hours  at  not  less  than  96°C.  This  method  does 
not  apply  to  other  fruits.  The  legal  limit  for  moisture  in  dried  apples 
is  24  per  cent.  Legal  limits  for  moisture  in  other  dried  fruits  and  vege- 
tables have  not  been  adopted. 

B.  Sugar  in  dried  fruits  may  be  determined  as  outlined  on  page  — . 

C.  Sulphurous  acid  in  sulphured  fruits  may  be  determined  as  out- 
lined on  page  100. 

4.  Refreshing  Test. — A.  Place  an  accurately  weighed  amount  of  dried 
fruit  or  vegetable  (l/2  pound  or  less)  in  a  pot  and  cover  with  boiling 
water  and  allow  to  stand  12  to  24  hours. 

B.  Drain   on   a  piece   of   screen   of   %-inch   mesh   and   record   the 
increased  weight  of  the  product. 

C.  Return  the  drained  product  to  the  liquid  and  boil  gently  until 
tender,  adding  sugar,  salt  or  spices  to  taste. 

D.  Note  the  color,  odor  and  flavor  of  the  cooked  product. 

Suggestions : 

1.  A  brief  description  of  the  standard  grades  of  California  dried  fruits 
is  given  in  Table  X. 

TABLE  X. — GRADES  OP  CALIFORNIA  DRIED  FRUITS 

APPLES,  Evaporated  (Artifically  dried): 

Extra  Fancy. — Fairly  uniform  size  rings;  uniform  white  color;  clean;  free  from  skins, 
cores,  stems,  bruised  or  rotten  spots,  worm  holes  or  screening. 

Fancy. — Fairly  uniform  size  rings;  uniform  white  or  very  light  yellow  color;  clean; 
almost  free  from  skins,  cores,  stems,  bruised  or  rotten  spots,  worm  holes  or  screenings. 

Extra  Choice. — Rings  of  fairly  uniform  white  or  light  yellow  color;  not  more  than 
25  per  cent  of  pieces  showing  skins,  cores,  stems,  bruised  or  rotten  spots  or  worm  holes; 
fairly  free  from  screenings. 

Choice. — Rings  of  white,  yellow  or  light  brown  color;  not  more  than  50  per  cent  of 
pieces  showing  skins,  cores,  stems,  bruised  or  rotten  spots,  worm  holes;  may  contain 
noticeable  amount  of  screenings. 

Standard. — Brown  color;  large  percentage  of  pieces  showing  skins,  cores,  stems, 
bruised  or  rotten  spots  and  of  screenings. 

APRICOTS,  California  Sun  Dried: 

Size  Grades. — Extra  Fancy,  over  48/32  inches  diameter. 
Fancy  48/32  inches  diameter. 

Extra  Choice,          40/32  inches  diameter. 
Choice,  32/32  inches  diameter. 

Standard,  below      32/32  inches  diameter. 

Quality  Grades. — Dried  apricots  are  sold  according  to  variety  and  locality,  Blenheims 
and  Moorparks  predominating  in  the  Santa  Clara  Valley  and  the  Royal  in  the  Sacra- 
mento and  San  Joaquin  Valleys  and  southern  California.  Two  general  quality  grades 
are  recognized: 

First. — Bright  colored,  well  bleached,  meaty,  clean,  neatly  cut  halves. 

Second. — Darker,  not  so  well  bleached,  thinner,  or  ragged  edges. 


66  LABORATORY  MANUAL  OF 

FIGS,  California  Sun  Dried: 
Black  Figs  (Mission  Variety): 

Fancy,  over  34/32  inches  diameter. 

Choice,          34/32  inches  diameter. 

Standard,      28/32  niches  diameter. 

White  Figs  (Calimyrna  and  Adriatic  Varieties): 
Fancy,  over  42/32  inches  diameter. 
Choice,          42/32  inches  diameter. 
Standard,      34/32  inches  diameter. 

PEACHES,  California  Sun  Dried: 

Size  Grades. — Extra  Fancy,  over  58/32  inches  diameter. 

Fancy,  58/32  inches  diameter. 

Extra  Choice,          50/32  inches  diameter. 

Choice,  42/32  inches  diameter. 

Standard,  34/32  inches  diameter. 

Classes. — Dried  peaches  are  divided  into  two  broad  classes,  namely  "Muirs"  and 
"Yellows,"  the  latter  including  several  yellow-fleshed,  freestone  varieties,  principally 
the  Lovell  and  Elberta.  Dried  peaches  are  sold  both  unpeeled  and  "Practically  Peeled," 
the  latter  term  designating  peaches  which  have  had  the  fuzzy  skin  removed  after  being 
dried. 

PEARS,  California  Sun  Dried: 

Because  of  their  distinctive  shape,  dried  pears  are  graded  by  hand  according  to  their 
size,  color  and  general  appearance  into  Extra  Fancy,  Fancy,  Extra  Choice,  Choice 
and  Standard  grades  for  which  no  simple  definitions  can  be  given. 

PRUNES,  California  Sun  Dried: 

Size  Grades. — No.  per  Pound.     Diameter  of  Grader  Holes. 

20  to  30  over  40/32  inches 

30  to  40  40/32  inches. 

40  to  50  38/32  inches. 

50  to  60  36/32  inches. 

60  to  70  33/32  inches. 

70  to  80  32/32  inches. 

80  to  90  30/32  inches. 

90  to  100  28/32  inches. 

100  to  110  26/32  inches. 

110  to  120  24/32  inches. 
120  and  up         below  24/32  inches. 

Quality  Grades. — Dried  prunes  are  sold  according  to  locality  where  grown,  such  as 
Santa  Clara,  Sacramento,  San  Joaquin,  Sonoma  or  Napa  Valleys.  Two  general  quality 
grades  are  known: 

First. — Uniform  amber  colored  meat  of  fine  flavor;  skin  in  good  condition  and  of 
deep  black  color. 

Second. — Brown  colored  flesh,  not  so  meaty  and  fine  flavored;  reddish  brown  colored 
skin. 

RAISINS,  California  Sun  Dried: 
A.  Muscat  Raisins  (with  seeds). 


FRUIT  AND  VEGETABLE  PRODUCTS  67 

1.  Layers  (unbroken  bunches  of  perfect  raisins), 
(a)  Vineyard  Run. 

(6)  Layers  (Three  crown  size),  see  below. 

(c)  Clusters  (Four  crown  size),  see  below. 

(d)  Imperials  (Six  crown  size),  see  below. 

2.  Loose  Muscats  (stemmed  raisins) : 

(a)  One  crown,  13/32  inches  diameter. 

(6)  Two  crown,  17/32  inches  diameter. 

(c)  Three  crown,        21/32  inches  diameter. 

(d)  Four  crown,  over  21/32  inches  diameter. 

3.  Seeded  Muscats  (above  sizes  of  stemmed  and  seeded  raisins): 

B.  Sultanina  Raisins  (seedless): 

1.  Natural  (stemmed  raisins): 

(a)  First,  plump  raisins  of  even  color  and  size. 

(b)  Second,  uneven  color  or  size  and  not  well  filled  out. 

2.  Bleached  (bleached  to  a  light  yellow  color) : 

(a)  Extra  Fancy,  fine  large  raisins  of  even  yellow  color. 

(b)  Fancy,  not  perfectly  bleached. 

(c)  Choice,  inferior  to  above  grades. 

3.  Oil  and  Soda  Dipped. 

C.  Miscellaneous    Varieties. — Sultanas,    practically    seedless;    Valencias,    bleached 
Muscats;  Malagas  and  Feherzagos  are  stemmed  and  packed  in  the  same  way  as  loose 
Muscat  raisins. 

D.  Currants. — Very  small,  stemmed,  seedless  raisins  obtained  from  the  Zante  or 
Black  Corinth  grapes. 


ASSIGNMENT  XXIV.— EXPERIMENTAL  DRYING  OF 
FRUITS  AND  VEGETABLES 

Materials. — Fresh  fruits  and  vegetables  in  season  as  directed  under 
''Procedure." 

Procedure : 

1.  Comparison  of  Sun-drying  and  Dehydration. — Prepare  two  trays 
each  of  apples  and  white  potatoes   as  directed  in  Assignment  XXV. 
Record  the  exact  weight  of  material  on  each  tray  before  and  after  prepa- 
ration.   Place  one  tray  of  each  product  in  a  sunny  location  out  of  doors 
and  record  the  loss  in  weight  daily  until  sufficiently  dry.    Do  not  expose 
during  moist  weather.    Place  the  other  tray  of  each  product  in  a  small 
air-blast  dehydrater  at  150°F.,  and  record  the  loss  in  weight  hourly 
until  sufficiently  dry.    Plot  the  comparative  rates  of  drying.     Compare 
the  cleanliness,  color,  flavor  and  odor  of  the  refreshed  and  cooked  prod- 
ucts.    If  procurable,  interesting  comparisons  can  be  obtained  by  using 
a  green  vegetable,  such  as  spinach  or  string  beans,  or  fruits  such  as 
bananas,  pears  and  berries. 

2.  Effect  of  Lye-dipping. — Weigh  accurately  two  equal  tray-loads  of 
prunes,  grapes  or  cherries.     Dip  one  lot  in  boiling  0.5  per  cent,  sodium 
hydroxide  solution  until  the  bloom  is  removed  and  the  skins  slightly 
checked.    Muscat  and  wine  grapes  require  a  2.5  per  cent,  solution.   Rinse 
in  cold  water  and  spread  on  a  tray.     Dry  both  trays  in  an  air-blast 
dehydrater  at  150°  to  160°F.     Record  the  loss  in  weight  hourly  and 
plot  the  comparative  rates  of  drying.    Compare  the  dried  samples  as  to 
color  and  flavor. 

3.  Effect  of  Blanching. — Prepare  two  weighed  trays  each  of  one  or 
more  products  such  as  spinach,  peas,  cubed  potatoes,  sliced  pumpkin, 
and  cubed  carrots.    Blanch  one  tray  of  each  in  a  steam  box;  potatoes 
3  minutes,  other  vegetables  5  minutes.     Dry  all  trays  in  an  air-blast 
dehydrater  at  150°F.,  plotting  the  hourly  losses  in  weight.    Compare  the 
color  and  flavor  of  each  before  and  after  cooking. 

4.  Effect  of  Sulphuring. — Prepare  two  trays  each  of  one  or  more 
products  such  as  peeled  and  sliced  apples,  halved  and  pitted  apricots  or 
peaches,  or  peeled  halved  pears.     Expose  one  tray  of  freshly  prepared 
fruit  to  the  fumes  of  burning  sulphur  for  1  hour.     (Caution:  Sulphured 
fruits  must  not  be  dried  on  metal  trays.    Use  wooden  slat-bottom  trays.) 

68 


69 


Dry  all  trays  in  an  air-blast  dehydrater  at  150°F.  and  compare  the 
color  and  flavor  of  the  dried  products. 

5.  Effect  of  Size  of  Pieces  on  Drying. — Prepare  four  trays  of  peeled 
and  cored  apples  as  follows: 

A.  Halves,  B.  quarters,  C.  slices  14  inch  thick,  D.  i/j-inch  cubes. 


FIG.  11. — Air  Blast  Dehydrater  in  Fruit  Products  Laboratory,  University  of  Cali- 
fornia. A.  Multivane  fan;  B,  Air  heating  chamber;  C,  Drying  chamber;  D,  Tray 
doors,  E,  Motor;  F,  Itecording  thermometer. 

Place  equal  weights  on  each  of  the  four  trays  and  sulphur  30  minutes. 
Dry  in  an  air-blast  dehydrater  at  150°F.,  till  each  lot  reaches  the  same 
degree  of  dryness  (about  20  per  cent,  moisture).  Plot  comparatively  the 
rates  of  drying  from  hourly  weights  and  compare  the  dried  samples  as 
to  color  and  flavor. 

6.  Effect  of  Temperature  of  Air  on  Drying. — Prepare  three  weighed 
trays  of  apples  by  peeling  and  coring,  slicing  or  cubing  and  sulphuring 
30  minutes.  Dry  one  tray  at  120°F.,  one  at  150°F.,  and  one  at  200°F., 


70  LABORATORY  MANUAL  OF 

until  sufficiently  dry  (about  20  per  cent,  moisture),  keeping  the  humidity 
and  velocity  of  air  as  constant  as  possible.    Record  results  as  in  5. 

7.  Effect  of  Humidity  of  Air  on  Drying. — Prepare  two  weighed  trays 
of  cubed  and  blanched  potatoes  or  cubed  and  sulphured  pears.    Dry  one 
tray  in  an  air-blast  dehydrater  at  150°F.,  with  air  of  low  relative  hu- 
midity (below  10  per  cent.).     Dry  the  other  tray  with  the  same  tem- 
perature and  velocity  of  air,  but  increase  the  relative  humidity  of  the  air 
to  at  least  40  per  cent.     This  may  be  accomplished  by  injecting  the 
proper  amount  of  steam  into  the  heated  air,  measuring  the  humidity  by 
a  Hygrodeik  or  by  wet  and  dry  bulb  thermometers.     Record  results 
as  in  Assignment  XXIV  6. 

8.  Effect  of  Velocity  of  Air  on  Drying. — Prepare  two  weighed  trays 
of  cubed  and  blanched  potatoes  or  cubed  and  sulphured  apples.     Dry 
one  tray  in  an  air-blast  dehydrater  at  150°F.,  in  a  vigorous  blast  of  air 
(500  to  1,000  linear  feet  per  minute  over  trays,  as  measured  with  an 
anemometer) .    Dry  the  other  tray  at  the  same  temperature  and  humidity 
but  in  a  mild  flow  of  air  (below  100  linear  feet  per  minute)  either  in  a 
natural  draft  evaporator  or  in  an  air-blast  dehydrater  with  restricted 
air-flow.     Record  results  as  in  Assignment  XXIV  6. 

9.  Comparison  of  Counter  Current  and  Parallel  Current  Systems  of 
Dehydration. — Prepare  two  trays  containing  equal  weights  of  apples, 
peeled,  cored,  cubed  or  sliced  and  sulphured.    Dry  one  tray  in  an  air-blast 
dehydrater,  using  an  initial  temperature  of  210°F.,  reducing  the  tem- 
perature as  directed  below  to  a  finishing  temperature  of  160°F.    Dry  the 
other  tray  at  an  initial  temperature  of  110°F.,  and  a  finishing  tempera- 
ture of  160°F.    In  each  case  estimate  the  total  weight  of  moisture  which 
must  be  evaporated  from  the  apples  before  being  considered  dry.     At 
intervals  of  30  minutes  weigh  each  tray  and  increase  or  decrease  the 
temperature  by  the  number  of  degrees  obtained  by  multiplying  the  total 
temperature  range  of  50°  by  the  percentage  of  water  lost,  referred  to 
the  weight  which  must  be  evaporated. 

Example. — Five  hundred  grams  of  prepared  apples,  with  an  estimated 
drying  ratio  of  5:1,  must  lose  400  grams  of  moisture  in  drying.  After 
30  minutes  at  210°F.,  a  loss  of  100  grams  in  weight  is  noted,  or  25  per 
cent,  of  the  total  moisture  to  be  lost.  Twenty-five  per  cent,  of  50°  is 
12.5°.  Consequently  the  temperature  should  be  reduced  to  197.5°F. 
Similarly,  if  started  at  110°F.,  a  loss  in  weight  of  10  per  cent,  would 
indicate  that  the  temperature  should  be  raised  to  115°F. 

10.  Effect  of  Moisture  Content  on  Spoiling. — Prepare  three  weighed 
trays  each  of  one  or  more  products  such  as  (1)  peeled,  cubed  and 
blanched  potatoes,  (2)  peeled  and  sliced  or  cubed  apples  held  in  2  per 
cent,  brine  for  5  minutes,  (3)  lye-dipped  grapes  or  prunes,  (4)  peeled 
and  sliced  onions  dipped  in  2  per  cent,  brine  or  other  materials  prepared 


FRUIT  AND  VEGETABLE  PRODUCTS  71 

as  directed  in  Assignment  XXV.  Determine  the  approximate  percentage 
of  moisture  in  advance  in  a  representative  sample  of  the  material  to  be 
dried  as  described  in  Assignment  XXIII  for  apples.  Calculate  the  weight 
of  moisture  which  must  be  lost  from  each  tray  of  material  in  order  to 
obtain  finished  products  of  15,  25,  and  30  per  cent,  moisture,  respectively, 
for  fruits  and  5,  15,  and  25  per  cent.,  respectively,  for  vegetables.  Dry 
the  trays  at  150°F.  until  the  predetermined  weight  of  material  has  been 
reached  in  each  case;  note  the  condition  or  "feel"  of  the  product  and  seal 
in  tin  cans  or  glass  jars  stored  in  a  dark  place.  After  6  weeks  or  more 
examine  for  evidence  of  spoilage  or  deterioration  in  quality. 


ASSIGNMENT  XXV.— PRACTICE  IN  FRUIT  AND 
VEGETABLE  DRYING 

Materials. — Fresh  fruits  and  vegetables  in  season  as  suggested  in 
Table  XL 

Procedure : 

1.  Dehydration. — Prepare   and   dry   in   an   air-blast   dehydrater   or 
natural-draft  "Home"  evaporator  several  lots  of  fruits  and  vegetables  in 
season  as  directed  in  Table  XI.     For  each  lot  note  the  weight  of  raw 
material,  loss  in  preparation  and  loss  in  drying.    Vegetables  should  be 
dried  until  crisp  or  brittle  (generally  below  8  per  cent,  moisture).    All 
fruits  should  be  dried  to  a  pliable  leathery  texture   (approximately  20 
per  cent,  moisture),  not  hard  and  brittle,  except  berries  and  plums,  which 
require  quite  thorough  drying  to  prevent  spoiling.     Pack  at  once  in 
insect-proof  cans  or  cartons  and  store  in  a  dry  place. 

2.  Sun-drying  of  Fruits. — If  fruits  are  available  and  climatic  condi- 
tions favorable,  such  fruits  as  apricots,  cherries,  figs,  grapes,  peaches, 
pears  and  prunes  may  be  sun-dried.     The  fruit  should  be  prepared  as 
in  Table  XI,  except  that  fruit  requiring  sulphuring  should  be  exposed 
to  the  fumes  of  burning  sulphur  for  3  to  4  hours.     Grapes  are  usually 
sun-dried  without  dipping  or  sulphuring.     Pears  are  usually  sun-dried 
after  merely  cutting  in  half,  sulphuring  24  to  72  hours  and  drying  largely 
in  the  shade.    After  the  fruit  is  two-thirds  to  three-fourths  dry  the  trays 
should  be  stacked  and  the  drying  completed  in  the  shade.    When  thor- 
oughly dry,  empty  the  dried  fruit  into  boxes  and  allow  the  moisture 
content  to  equalize  for  several  weeks.    Dip  in  boiling  water  2  minutes, 
drain  off  the  surface  moisture  and  pack  in  insect-proof  cans  or  cartons. 
Sulphured  fruits  are  usually  resulphured  for  several  hours  after  dipping 
and  before  packing  in  order  to  preserve  the  color. 

3.  Examination  of  Samples. — After  at  least  one  month's  storage,  note 
the  color  and  flavor  of  each  of  the  dried  products.     Make  a  careful 
comparison  of  samples  of  the  same  variety  of  fruit,  one  sun-dried  and 
the  other  dehydrated.     Examination  should  be  made  both  before  and 
after  preparation  for  the  table  as  in  Assignment  XXIII-4. 

Suggestions : 

1.  Dried  fruits  may  be  graded  in  accordance  with  the  sizes  given  in 
Table  X. 

72 


FRUIT  AND  VEGETABLE  PRODUCTS 


73 


2.  Dried  products  which  have  become  insect-infested  can  be  fumi- 
gated to  destroy  insect  life  by  placing  in  a  tight  container  together  with 


Fia.  12. — Natural  draft  home  size  evaporator.     A,  Heat  spreader;  B,  Tray;  C,  Coa 

oil  stove;  D,  Air  outlet. 


a  pan  of  liquid  carbon  bisulphide  in  the  proportion  of  1  pound  per  100 
cubic  feet  until  the  carbon  bisulphide  has  evaporated. 


74 


LABORATORY  MANUAL 


TABLE  XI. — DIRECTIONS  FOR  DEHYDRATION  OF  FRUITS  AND  VEGETABLES 


Product 

Preparation  for  Tray 

Lbs.  per 

Sq.  Ft. 

on  Tray 

Treatment  on 
Tray 

Safe 
Finishing 
Temperature 

Apples  .... 

Peel  and  core,  then  slice 

2 

Sulphur  30  min. 

165°F 

Apricots  

or  cube 
Halve  and  pit 

2 

Sulphur  60  min. 

160°F. 

Bananas  

Peel,   then   halve  length- 

1 to2 

Sulphur  30  min. 

165°F. 

Berries,     Black-, 
Logan  -  and 
Raspberries 
Berries,  Straw-.  . 
Cherries  

wise  or  slice  crosswise 
Sort;  wash  if  necessary 

Hull  and  sort 
Dip  in  boiling  J^  per  cent 

1  to  2 

1  to  2 
2  to  3 

Sulphur  15  min. 
(Optional) 

Sulphur  30  min. 
Sulphur  white 

160°F. 

160°F. 
170°F. 

Dates.  .    .    . 

soda  sol. 
Wash  gently 

2 

cherries  20  min. 

140°F. 

Figs.. 

Wash  thoroughly 

2  to  3 

Sulphur  Adriatic 

150°F. 

Grapes,  Sultana, 
Sultanina  .    . 

Dip  in  boiling  %  per  cent 
lye  sol.,  then  rinse 

3 

figs   1  hr.;  do 
not  sulphur 
other  varieties 
Sulphur  60  min. 

160°F. 

Grapes,    Muscat 
and  Wine  Va- 
rieties 
Peaches  

Dip    in    boiling    2}/£    per 
cent  lye  sol.,  then  rinse 

Halve  and  pit  (peeling  op- 

3 
3 

Sulphur  60  min. 
Sulphur  60  min. 

160°F  . 
150°F. 

Pears  

tional) 
Peel;  halve;  core  (cubing 

2  to3 

Sulphur  30  min. 

145°F. 

Plums  

optional) 
Halve  and  pit 

2  to  3 

Sulphur  60  min. 

160°F. 

Prunes  ...    . 

Dip  in  boiling  J^  per  cent 

3  to  4 

165°F. 

lye  sol. 

Beans;  string.  .  .  . 
Beets  

Prepare  as  for  canning 
Prepare    as   for   canning; 

2 
2 

Steam  blanching 

160°F. 
160°F. 

Cabbage  .  . 

slice  J4  inch  thick 
Shred;  blanch  2  min.   in 

1  to2 

150°F. 

Carrots  

boiling   1   per  cent  so- 
dium  bicarbonate  sol.; 
rinse 
Peel  and  cube 

2 

Blanch  in  steam 

150°F. 

Sweet  Corn  

Husk;  blanch  on  cob  in 

1  to2 

5  minutes 

160°F. 

Onion  

boiling  water  10  min.; 
cut  from  cob 
Peel;  slice  ^/g  inch  thick; 

1 

140°F.  * 

Peas  

dip  in  cold  3  per  cent 
brine 
Prepare  as  for  canning 

1  to2 

Steam  blanching 

150°F. 

Potatoes,  Sweet.  . 
Potatoes,  White  .  . 
Pumpkin  

Peel;  slice  J4  inch  thick 

Peel;  slice  or  cube;  dip  in 
boiling  water  2  min. 
Remove    seeds;    slice    or 

1  to2 

1  to  2 
2 

(optional) 
Blanch  in  steam 
5  min. 
Steam  blanching 
(optional) 
Steam  blanching 

150°F. 
150°F. 
170°F. 

Spinach  .  .  .  . 

shred  into  thin  pieces 
Wash  thoroughly 

1 

4  to  5  min. 

160°F. 

Tomatoes  .  . 

Slice  ^2  inch  thick,  or  peel 

1  to2 

Sulphur  30  min. 

150°F. 

and  halve 

(optional) 

ASSIGNMENT  XXVI.— PRACTICE  IN  THE  PREPARATION 
AND  REFINING  OF  FIXED  OILS 

Materials. — Dry  tomato  seeds  from  Assignments  IX  and  X,  dry 
apricot  pits  10  pounds,  or  dry  cherry  pits  5  pounds,  and  ripe  olives 
(unpickled  preferred)  20  pounds.  Rancid  oil,  1  quart. 

Procedure : 

1.  Preparation. — A.  Pits. — Weigh  accurately  about  4,000  grams  of 
apricot  pits  or  2,000  grams  of  cherry  pits.    Crush  the  pits;  separate  the 
kernels  and  weigh.    Grind  the  kernels  fine  with  a  food  chopper  and  weigh. 

B.  Tomato  Seeds. — Weigh  the  dry  tomato  seeds  from  Assignments 
IX  and  X  carefully.    If  the  seeds  are  not  "bone  dry,"  dry  to  constant 
weight  at  140°  to  150°F.    Grind  thoroughly  with  a  food  chopper,  using 
the  grinding  attachment.    Weigh  the  ground  material. 

C.  Olives. — Unpickled  ripe  olives  are  best,  but  pickled  ripe  olives  will 
answer  the  purpose  very  well.    Crush  the  weighed  fruit  thoroughly  in  a 
coffee-mill  or  heavy  sample-grinder,  crushing  the  pits  and  seeds  as  well 
as  the  flesh.    Weigh  the  crushed  fruit. 

2.  Extraction  of  Oil  by  Pressure. — A.  Fruit  Kernels. — Heat  the  finely 
ground  kernels  to  100°C.   (212°F.)   in  a  steam  box  in  layers  about  2 
inches  deep  between  the  folds  of  a  very  heavy  press-cloth.    While  still 
hot  place  the  layers  or  "cheeses"  of  material  between  the  wooden  racks 
of  a  powerful  press  and  subject  to  as  high  pressure  as  is  attainable  with 
the  available  equipment.    A  pressure  of  at  least  500  pounds  per  square 
inch  is  desirable.     Continue  the  pressing  until  no  more  oil  is  obtained. 
Grind  the  press  cake;  add  a  small  amount  (about  15  per  cent.)  of  hot 
water;  mix  well;  heat  to  212°F.  and  press  a  second  time.    Keep  the  oil 
from  the  two  pressings  separate.     Allow  the  water  and  oil  from  the 
pressings  to  settle  overnight.    Separate  the  oil  from  the  water  by  skim- 
ming or  siphoning.    Measure  the  oil  obtained  and  reserve  the  press  cake 
for  Assignment  XXVII. 

B.  Olives. — Press  as  directed  in  Assignment  XXVI  2  A,  but  do  not 
heat  the  fruit  at  any  stage  of  the  process.  Do  not  mix  the  liquids  from 
the  two  pressings.  Allow  the  juice  and  oil  to  settle  overnight  and  sepa- 
rate the  oil  from  the  juice  by  skimming  or  siphoning.  Measure  the  yield 
of  oil. 

3.  Extraction  by  Solvent. — Place  the  dry  ground  tomato-seeds  in  a 
Soxhlet  or  other  continuous  extractor  and  extract  for  12  hours  with  pure 

75 


76  LABORATORY  MANUAL 

benzene  (benzol).  Remove  the  solvent  from  the  oil  by  distillation. 
Weigh  the  residual  oil  and  note  its  character. 

4.  Refining  and  Filtering  Oils  from  Assignment  XXVI  2  and  3. — 
A.  Kernel  Oils. —  the  oils  from  the  first  and  second  pressings.     Note 

the  flavor,  color  and  odor  of  each.  Determine  the  percentage  of  free  oleic 
acid  in  a  10-gram  sample  by  titration  with  N/10  sodium  hydroxide  as 
directed  in  Appendix,  page  98.  Weigh  the  oil  and  add  exactly  enough  dry 
sodium  carbonate  (Na2C03)  to  neutralize  the  free  acid.  (One  gram  of 
sodium  carbonate  will  neutralize  5.32  grams  of  free  oleic  acid.)  Add  also 
2  c.c.  of  water  per  1,000  grams  of  oil  and  2  per  cent,  by  weight  of  finely 
ground  bone-black  or  vegetable  decolorizing  carbon.  Heat  the  mixture  to 
390°  to  200°  F.,  and  pass  a  stream  of  carbon  dioxide  through  it  at  this 
temperature  for  2  hours.  Allow  to  stand  overnight  at  room  temperature. 
Filter  through  dry  filter  paper  and  determine  the  yield.  Note  the  color, 
flavor  and  odor  of  each.  Store  each  oil  in  a  tightly  stoppered  bottle 
in  a  dark  place  for  3  months  and  again  examine  for  flavor,  color  and  odor. 

B.  Olive  Oil  from  Unpickled  Olives. — Oil  from  unpickled  olives  will 
be  bitter.    Mix  the  oil  from  each  pressing  separately  with  three  times 
its  volume  of  water  at  100°  to  105°F.    Allow  to  settle.    Separate  the  oil 
from  the  water  by  skimming  and  repeat  the  washing  and  settling  process 
until  each  oil  is  free  from  bitterness.     Filter  through  dry  filter  paper. 
Store  in  tightly  stoppered  bottles  in  a  dark  place  for  3  months  and  then 
note  the  flavor,  color  and  odor  of  each. 

C.  Olive  Oil  from  Pickled  Olives. — Oil  from  pickled  ripe  olives  is 
not  bitter  and  requires  no  washing  with  water.    Filter  through  dry  filter 
paper;  store  and  examine  as  in  Assignment  XXVI  4-JB. 

5.  Refining  Rancid  Oil. — Rancid  oil  can  often  be  rendered  edible  by 
refining  as  directed  in  Assignment  XXVI  4-A.     If  this  treatment  fails 
to  remove  all  objectionable  odor  and  flavor,  maintain  the  oil  at  a  tem- 
perature of  240°  to  250°F.  and  pass  a  stream  of  live  steam  through  it 
for  an  hour ;  cool  and  filter. 

Heating  to  190°F.  with  3  to  4  per  cent,  of  finely  ground  Fuller's  Earth 
and  filtering  will  sometimes  remove  objectionable  odors  and  flavors. 


ASSIGNMENT  XXVIL— PRACTICE  IN  THE  PREPARATION 
OF  ESSENTIAL  OILS 

Materials. — Oranges  or  lemons,  100  pounds.  Apricot  kernel  or  cherry 
kernel  press-cake  from  Assignment  XXVI.  Apricot  or  cherry  pits  3 
pounds,  or  kernels  2  pounds. 

Procedure: 

1.  Essential  Oil  from  Oranges  or  Lemons. — A.  By  Pressure. — Weigh 
carefully  about  ^2  box  of  oranges  or  lemons.  Remove  the  yellow  portion 
of  the  rinds,  including  the  oil  cells,  by  grating  down  to  the  white  "rag." 
Grind  the  gratings  finely  and  place  in  a  heavy  cloth.  Press  under  as 
heavy  pressure  as  can  be  obtained  and  collect  the  juice.  To  the  pomace 
add  an  equal  volume  of  warm  water;  mix  and  press  a  second  time.  Do 
not  mix  the  two  pressings.  Place  the  juice  and  oil  of  each  in  a  large  cen- 
trifuge tube  and  centrifuge  until  the  oil  and  juice  separate  into  distinct 
layers.  Separate  the  oil  from  the  juice  by  means  of  a  glass  separatory 
funnel.  Filter  the  oil  through  dry  paper  to  break  the  emulsion  and  to 
clear  the  oil.  Measure  the  yield.  Mix  the  two  lots  of  oil  and  store  in 
a,  tightly  stoppered  bottle.  If  a  centrifuge  is  not  available  allow  the 
emulsions  of  juice  and  oil  to  settle  overnight  in  tall  tightly  stoppered 
separatory  funnels. 

B.  By  Solvent. — Remove  the  oil  cells  from  a  weighed  quantity  of 
oranges  or  lemons  by  grating  as  directed  in  Assignment  XXVII  1-A. 
Place  the  gratings  in  a  wide-mouth  glass-stoppered  bottle.     Add  from 
a  graduated  cylinder  sufficient  low-boiling  petroleum  ether  or  ethyl  ether 
to  cover  the  product.  Stopper  tightly  and  allow  to  stand  8  to  10  hours  with 
occasional   agitation.     Separate  the  solvent   from   the  peels  by   heavy 
pressure.     Separate  the  juice  from  the  solvent  by  means  of  a  separatory 
funnel.     Place  the  solvent  in  a  distillation  flask  resting  in  a  water-bath 
and  connect  to  a  glass  condenser.     Distill  at  50°C.  (122°F.)  until  most 
of  the  solvent  has  been  separated  from  the  oil.     Measure  the  volume  of 
distillate  and  calculate  the  loss  of  solvent.     Place  the  oil  in  a  shallow 
beaker  at  room  temperature  until  practically  all  odor  of  the  solvent  has 
disappeared.     Determine  the  yield  of  oil  and  compare  the  quality  with 
that  from  Assignments  XXVII  1-4  and  C 

C.  By  Distillation. — Place  gratings  obtained  as  in  Assignment  XXVII 
1-A  from  a  weighed  quantity  of  lemons  or  oranges,  in  a  large,  heavy - 

77 


78  LABORATORY  MANUAL  OF 

walled  bottle.  Fit  the  bottle  with  a  two-hole  rubber  stopper.  Insert 
through  the  stopper  a  ^4-inch  glass  tube  reaching  to  within  ^4  inch  of  the 
bottom  of  the  bottle.  Connect  this  tube  to  a  source  of  steam,  such  as  a 
large  flask  of  boiling  water.  Connect  the  bottle  containing  the  peels  to 
a  glass  condenser  fitted  to  a  large  suction  flask,  the  latter  in  turn  con- 
nected to  a  vacuum  pump.  Insert  the  bottle  with  the  peels  in  a  large  pot 
of  water  at  180°  to  190°F.  and  pass  steam  through  the  peels  under  a 
vacuum  of  25  to  28  inches.  Collect  the  distillate  until  no  more  oil  collects 
in  the  receiving  flask.  Allow  the  distillate  to  stand  overnight.  Separate 
the  oil  by  means  of  a  separatory  funnel  and  compare  with  oils  from 
Assignments  XXVII  l-A  and  B. 

Store  in  glass  bottles  for  3  months  and  again  compare  the  various 
samples. 

2.  'Bitter  Almond"  Oil  from  Apricot  or  Cherry  Pits. —  A.  Preparation 
of  Press-Cake. — Grind  the  press-cake  from  Assignment  XXVI  and  weigh. 
To  each  100  grams  of  the  ground  material  add  about  1,000  c.c.  of  water 
and  boil  gently  for  20  minutes  to  extract  the  amygdalin. 

B.  Addition  of  Kernels.— Cool  to  45°C.   (113°  to  115°F.)   and  add 
for  each  100  grams  of  original  dry  press-cake  10  grams  of  finely  ground 
apricot  or  cherry  kernels,  which  have  not  been  heated  previously.    The 
ground  kernels  are  conveniently  added  after  mixing  in  six  or  seven  times 
their  volume  of  cold  water.     Mix  the  kernels   and   boiled   press-cake 
thoroughly  and  maintain  at  45°C.  for  1  hour. 

C.  Distillation. — Transfer  the  mixture  to  a  large  bottle.    Arrange  for 
steam  distillation  as  in  Assignment  XXVII  1-C,  but  do  not  use  a  vacuum 
pump.     Distill  at  atmospheric  pressure  with  the  bottle  containing  the 
ground  press-cake,  etc.,  immersed  in  boiling  water.     Continue  the  distilla- 
tion until  all  of  the  bitter-almond  oil  has  been  removed,  as  indicated  by 
the  absence  of  milkiness  in  the  condensed  vapors.     Place  the  distillate 
in  a  glass  distillation  flask  and  distill  by  boiling  over  a  direct  flame  until 
one-half  of  the  liquid  has  been  distilled.     Redistill  this  distillate  (known 
as  cohobation)  three  or  four  times,  reducing  the  volume  approximately 
one-half  each  time.     Separate  the  oil  from  the  remaining  water  by  means 
of  a  separatory  funnel  and  determine  the  yield. 

Caution. — Prussic  acid  is  formed  during  the  process  and  distills  with 
the  bitter-almond  oil  (benzaldehyde).  Do  not  inhale  the  vapors  from 
the  still.  While  the  danger  is  not  very  great,  unnecessary  exposure  to 
the  prussic  acid  fumes  should  be  avoided. 

Suggestions : 

1.  The  peeled  lemons  may  be  used  for  the  preparation  of  citric  acid 
in  Assignment  XXXI  and  the  oranges  may  be  used  for  juice  or  vinegar. 

2.  Bitter-almond  oil    (benzaldehyde)    is  formed  from  the  glucoside 


FRUIT  AND  VEGETABLE  PRODUCTS  79 

amygdalin,  the  bitter  principle  of  the  kernels  in  fruit  pits.  The  reaction 
is  induced  by  the  enzyme,  EMULSIN,  which  also  exists  in  the  kernels. 
The  reaction  takes  place  very  rapidly  at  45°  C.,  as  follows: 

C20H27NOu         +2H2O   =   HCN  +C6H6CHO  +2C2H12O6 


Amygdalin          + Water   =  Prussic  Acid         +Benzaldehyde          -(-Glucose 


ASSIGNMENT  XXVIIL— EXAMINATION  OF  COMMERCIAL 

VINEGARS 

Materials. — Samples  of  cider,  grape,  malt  and  distilled  vinegars. 

Procedure : 

1.  Appearance. — Examine  and  compare  the  samples  for  color,  clear- 
ness, sediment,  flavor  and  odor.     Hold  a  small  sample  in  a  test  tube 
toward  the  light  and  examine  carefully  with  a  hand  lens  for  presence 
of  "vinegar  eels"  (minute  nematode  worms). 

2.  Total  Acid  as  Acetic. — Transfer  a   10-c.c.  sample  to  a   100-c.c. 
volumetric  flask.    Dilute  to  mark  with  distilled  water  and  mix.    Deter- 
mine the  acid  in  a  10-c.c.  aliquot  of  the  diluted  sample  as  directed  on 
page  98.     Also  determine  the  total  acid  by  means  of  a  Leo  Acid  Tester, 
following  the  directions  accompanying  the  apparatus. 

3.  Volatile  Acid  as  Acetic. — Place  10  c.c.  of  the  vinegar  in  a  porcelain 
evaporating  dish  on  a  steam  bath.     Evaporate  almost  to  dryness.     Add 
20  c.c.  of  water  and  evaporate  again  almost  to  dryness.     Repeat  addi- 
tions of  water  and  evaporations  at  least  five  times.    Take  up  the  residue 
in  water  and  titrate  with  N/10  sodium  hydroxide.    Report  as  fixed  acid 
in  terms  of  acetic  acid.     Total  acid  minus  fixed  acid  gives  the  volatile 
acid  as  acetic  acid. 

4.  Extract. — With  a  pipette  place  25  c.c.  of  the  vinegar  in  a  tared 
evaporating  dish  about  200  mm.  wide.     Evaporate  to  a  syrupy  con- 
sistency over  a  steam  bath.    Dry  1  hour  at  100°C.  in  a  drying  oven  and 
weigh.    Calculate  grams  of  extract  per  100  c.c. 

5.  Alcohol. — Place  200  c.c.  of  the  sample  in  a  500-c.c.  distillation 
flask.     Neutralize   with    concentrated   sodium   hydroxide,   using    litmus 
paper  as  an  indicator. 

Distill  about  95  c.c.  into  a  100-c.c.  volumetric  flask.  Dilute  to  mark. 
Determine  the  specific  gravity  by  means  of  a  hydrometer,  Westphal 
balance  or  pycnometer  at  15%°C. 

From  the  alcohol  table  in  "Food  Analysis"  by  Leach  determine  the 
corresponding  alcohol  content  of  the  distillate.  This  figure  divided  by 
two  gives  the  alcohol  content  of  the  vinegar. 

Alcohol  in  excess  of  %  per  cent,  indicates  incomplete  acetic  acid 
fermentation. 

6.  Sugar. — Determine  total  sugar  after  inversion  as  directed  in  the 
Appendix,  page  100. 

80 


FRUIT  AND  VEGETABLE  PRODUCTS  81 

Suggestions : 

1.  Vinegar  Standards. — A.  Pure  cider  vinegar  contains  in  each  100 
c.c.  not  less  than  4  grams  of  acetic  acid,  1.6  grams  of  extract  (of  which 
not  more  than  50  per  cent,  is  reducing  sugars) ,  and  .25  grams  apple  ash. 

Diluted  cider  vinegar  must  contain  not  less  than  4  grams  of  acetic 
acid  per  100  c.c.,  but  need  not  conform  to  the  other  standards  if  labeled 
"diluted." 

B.  Malt  vinegar  contains  in  each  100  c.c.  not  less  than  4  grams  of 
acetic  acid,  2  grams  of  solids  and  0.2  grams  of  ash. 

C.  Wine  vinegar  or  grape  vinegar  contains  in  100  c.c.  not  less  than 
4  grams  of  acetic  acid,  1.0  gram  of  grape  solids  and  0.13  grams  of 
grape  ash. 

D.  Distilled  vinegar,  spirit  vinegar  or  grain  vinegar  is  made  by  the 
acetification  of  dilute  alcohol  and  contains  in  100  c.c.  not  less  than  4 
grams  of  acetic  acid. 

An  exact  interpretation  of  the  above  standards  would  require  that 
the  4  grams  of  acid  per  100  c.c.  be  all  acetic  acid.  In  practice,  however, 
the  total  acid  is  determined  and  calculated  as  acetic,  although  part  of 
the  total  acid  may  be  due  to  other  organic  acids.  The  addition  of  min- 
eral acids  to  vinegar  is  prohibited. 

2.  Definition  of  "Grain  Strength." — The  trade  usually  designates  the 
strength  of  vinegar  by  "grains"  instead  of  in  percentage.  A  "40-grain 
vinegar"  contains  4  grams  of  total  acid  per  100  c.c.  calculated  as  acetic 
acid.  That  is,  "10  grains"  is  equivalent  to  "1  gram  of  acid  as  acetic  per 
100  c.c." 


ASSIGNMENT    XXIX — EXPERIMENTAL   PREPARATION 
OF  CIDER  VINEGAR 

Materials. — Twenty  pounds  of  apple  culls. 

Procedure : 

1.  Preparation  of  Pure  Yeast  Starter. — Obtain  a  pure  culture  of  cider 
yeast  (Saccharomyces  ellipsoideus  or  S.  malei)  on  agar.     Add  a  small 
amount  of  sterile  cider.    Incubate  3  to  4  days  at  80°  to  90°F.    Transfer 
the  actively  fermenting  culture  to  500  c.c.  of  sterile  cider  in  a  cotton- 
plugged  flask  and  incubate  at  80°  to  90°F.  until  in  active  fermentation. 

2.  Crushing  and  Pressing. — Extract  the  juice  from  a  weighed  amount 
of  apple  culls  as  directed  in  Assignment  XIII.     Determine  the  yield, 
acidity  of  the  juice,  and  Balling  degree. 

3.  Alcoholic  Fermentation. — Divide  into  two  equal  portions  and  place 
each  half  in  a  1-gallon  stoneware  crock.    Place  both  crocks  in  an  incu- 
bator at  80°  to  90 °F.,  or  in  a  warm  room. 

A.  Spontaneous  Fermentation. — Cover  one  crock  with  cheese  cloth 
and  allow  to  undergo  fermentation  without  addition  of  yeast. 

B.  Pure  Yeast  Fermentation. — To  the  second  crock  of  juice  add  the 
actively  fermenting  pure  yeast  culture  from  Assignment  XXIX  1  at  the 
rate  of  50  c.c.  per  1,000  c.c.  of  cider.     Mix  thoroughly. 

Determine  the  Balling  degree  of  each  lot  daily  until  fermentation 
ceases.  Fermentation  will  usually  be  complete  in  2  to  3  weeks.  Examine 
samples  of  each  juice  under  the  high  power  of  the  microscope  on  the 
second  and  third  days  of  fermentation  and  make  sketches  of  micro- 
organisms found. 

Determine  the  alcohol  and  sugar  in  the  fermented  juices  as  directed 
in  Assignment  XXVIII.  Calculate  the  yield  of  alcohol  per  gram  of 
sugar  fermented  in  each  case. 

4.  Acetic   Fermentation. — Decant   the    fermented    liquids    from    the 
yeast  sediment  and  strain  through  several  thicknesses  of  cheese  cloth. 
Rinse  the  containers  used  for  alcoholic  fermentation  and  return  the  fer- 
mented liquids  to  them. 

Allow  lot  3- A  (spontaneously  fermented  juice)  to  remain  untreated. 

To  lot  3-5  add  one-fourth  its  volume  of  bulk  cider  vinegar  (not  pas- 
teurized bottled  vinegar). 

Determine  the  acidity  of  each  lot.  Cover  both  crocks  with  cloth 
to  exclude  vinegar  flies  and  place  in  an  incubator  at  80°  to  90°F.  or  in 

82 


FRUIT  AND  VEGETABLE  PRODUCTS  83 

a  warm  room.    Determine  the  acidity  of  each  at  intervals  of  one  week 
until  there  is  no  longer  any  increase  in  acidity. 

Determine  the  residual  alcohol  as  directed  in  Assignment  XXVIII. 
Calculate  the  amount  of  alcohol  oxidized  during  acetic  fermentation. 

5.  Clarification. — A.  Filtration. — Determine  the  rate  of  filtration  of 
100  c.c.  portions  of  each  vinegar  through  a  small  filter  paper.    To  100 
c.c.  portions  add  2  grams  of  "Filter  eel"  or  other  infusorial  earth,  and 
to  a  third  100-c.c.  portion  of  each  add  4  grams  of  this  material.     Mix 
well  and  again  determine  the  rate  of  filtration  of  each.     Compare  the 
clearness  and  flavor  of  the  filtrate  from  each  lot. 

B.  Clarification  with  Isinglass. — Prepare  a  2  per  cent,  solution  of 
Russian  isinglass  (fish  glue)  or  other  good  grade  of  isinglass  by  soaking 
2  grams  of  the  material  in  100  c.c.  of  vinegar  for  24  hours  and  grinding 
in  a  mortar  until  dissolved. 

To  100-c.c.  lots  of  each  vinegar  add  the  following  amounts  of  isinglass 
by  means  of  this  solution: 

(1)  5  grams  per  hectoliter 0.25  c.c.  per  100  c.c. 

(2)  10  grams  per  hectoliter 0.50  c.c.  per  100  c.c. 

(3)  20  grams  per  hectoliter 1.00  c.c.  per  100  c.c. 

(4)  40  grams  per  hectoliter 2.00  c.c.  per  100  c.c. 

(5)  80  grams  per  hectoliter 4.00  c.c.  per  100  c.c. 

Shake  thoroughly  and  allow  to  stand  48  hours.  Compare  results. 
To  lots  which  have  not  settled  add  1,000  grams  Spanish  Clay  per  hecto- 
liter as  directed  in  5-C  and  note  results. 

C.  Spanish  Clay. — Prepare  a  10  per  cent,  suspension  of  Spanish  Clay 
as  directed  in  Assignment  XII-6-C.     To  100-c.c.  lots  of  each  vinegar 
add  the  following  amounts  of  this  clarifying  agent  (dry  basis) : 

(1)  100  grams  per  hectoliter 1  c.c.  per  100  c.c. 

(2)  200  grams  per  hectoliter 2  c.c.  per  100  c.c. 

(3)  400  grams  per  hectoliter 4  c.c.  per  100  c.c. 

(4)  800  grams  per  hectoliter 8  c.c.  per  100  c.c. 

(5)  1GOO  grams  per  hectoliter 16  c.c.  per  100  c.c. 

Allow  to  stand  48  hours  and  compare  results. 

6.  Pasteurizing. — Combine  the  clear  vinegar  from  4-^4,  4-B,  and  4-C, 
keeping  the  two  original  lots  of  vinegar  separate.    Bottle  and  seal  with 
crown  caps.     Pasteurize  one-half  of  each  lot  at  140°F.  for  20  minutes. 
Place  all  bottles  in  an  incubator  at  80°  to  90°F.,  or  in  warm  rooms 
for  several  months.     Compare  the  clearness  of  pasteurized  and  unpas- 
teurized  samples. 

Suggestions. — Data  from  alcoholic  and  acetic  fermentations  should 
be  plotted  on  coordinate  paper  in  order  to  indicate  the  relative  rates  and 
completeness  of  fermentation. 


ASSIGNMENT   XXX.— PRACTICE   IN  THE   PREPARATION 
OF  FRUIT  VINEGARS 

Materials. — Cull  fruit,  such  as  apples,  oranges,  grapes,  pears,  peaches 
or  prunes,  50  pounds. 

Procedure: 

1.  Preparation  of  Yeast  Starter. — Prepare  about  1,000  c.c.  of  pure 
cider  yeast  starter  as  directed  in  Assignment  XXX- 1. 

2.  Preparation  of  Fruit. — A.  Juicy  Fruits. — Crush  and  press  juicy 
fruits,  such  as  oranges,  grapes  and  apples,  as  directed  in  Assignment 
XIII.    Record  the  weight  of  the  fresh  fruit  and  pomace  and  the  volume 
of  juice.     Determine  the  acidity  and  Balling  degree  of  each  juice  and 
place  each  in  a  stoneware  crock.     Dry  the  pomace  in  an  air-blast  dehy- 
drater  and  determine  the  yield  of  dried  material. 

B.  Pulpy  Fruits. — Thoroughly  crush  a  pulpy  fruit,  such  as  peaches, 
pears  or  prunes,  into  a  stoneware  crock.  Press  out  a  small  quantity  of 
the  juice  and  determine  the  acidity  and  Balling  degree.  If  the  Balling 
degree  exceeds  20°  add  a  calculated  amount  of  water  to  reduce  it  to  20°. 
Record  the  weight  of  fresh  fruit  used.  Do  not  press  until  after  pre- 
liminary fermentation  has  taken  place. 

3.  Fermentation. — A.  Juice. — To  each  1,000  c.c.  of  fresh  juice  add 
50  c.c.  of  an  actively  fermenting  pure  yeast  culture.    Mix  thoroughly  and 
cover  the  crock  with  a  cloth  to  exclude  vinegar  flies.    Store  in  a  warm 
place  at  80°  to  90°F.  and  allow  to  stand  until  fermentation  ceases.  Take 
the  Balling  degree  of  each  fermenting  juice  daily  and  plot  the  rate  of 
fermentation.     Fermentation  should  be  complete  within  15  days. 

B.  Pulpy  Fruits. — To  the  crushed  pears  or  other  pulpy  fruit  add  50 
c.c.  of  actively  fermenting  pure  yeast  starter  per  1,000  grams  of  fruit. 
Mix  thoroughly  and  cover  the  crock  with  cloth.  Stir  vigorously  twice 
daily  until  the  fruit  is  thoroughly  softened  by  fermentation  (usually  4 
to  5  days).  Determine  the  Balling  degree  daily.  Press  out  the  juice, 
weigh  the  pomace  and  measure  the  volume  of  juice  obtained.  Allow  the 
fermentation  to  proceed  as  in  2-A  until  there  is  no  further  reduction  in 
Balling  degree.  Record  the  Balling  degree  and  plot  the  rate  of  fermen- 
tation. 

4.  Clearing  the  Fermented  Juice. — Separate  the  fermented  juice  from 
the  yeast  sediment  and  filter  it  through  a  juice  filter  or  filter  paper. 

5.  Dilution  and  Addition  of  Acid. — Determine  the  total  acid  and 

84 


FRUIT  AND  VEGETABLE  PRODUCTS  85 

alcohol  content  of  the  fermented  juice  as  directed  in  Assignment  XXVIII. 
If  the  alcohol  is  in  excess  of  6  per  cent,  reduce  it  to  this  percentage  by 
the  addition  of  a  calculated  amount  of  water. 

To  each  1,000  c.c.  of  the  liquid  add  250  c.c.  of  strong  unpasteurized 
fruit  vinegar. 

6.  Acetification. — Store  the  filtered  and  acidified  liquid  at  80°  to 
85 °F.  in  a  stoneware  crock  covered  with  cheese  cloth.     Determine  the 
total  acidity  weekly  until  there  is  no  longer  any  increase.    Plot  the  rate 
of  acetic  fermentation. 

7.  Clearing  and  Bottling  the  Vinegar. — Filter  the  vinegar  and  meas- 
ure its  volume.    Calculate  the  yield  of  vinegar  in  gallons  per  ton  of  fresh 
fruit. 

Bottle  the  vinegar  in  crown-finish  bottles  and  seal  with  crown  caps. 
Pasteurize  as  directed  in  Assignment  XXIX-6. 

Suggestions: 

1.  Dried  unsulphured  fruits  may  be  used  for  the  preparation  of  vin- 
egar if  soaked  until  soft  in  sufficient  water  to  reduce  the  sugar  percentage 
to  20  and  then  crushed  and  fermented  as  directed  for  pulpy  fruits. 

2.  Potatoes   (sweet  or  white)   may  be  used  in  the  same  manner  as 
pulpy  fruits  for  vinegar  making  if  first  thoroughly  cooked  in  a  steam 
retort  at  5  pounds  pressure,  to  gelatinize  the  starch,  and  then  heated 
at  60°C.  (140°F.)  with  5  per  cent,  of  ground  barley  malt  until  the  starch 
is  converted  to  sugar.     Complete  conversion  of  the  starch  to  sugar  is 
shown  by  the  absence  of  blue  color  when  a  drop  of  the  "mash"  is  mixed 
with  a  drop  of  dilute  iodine  solution. 


ASSIGNMENT  XXXI.— PRACTICE  IN  THE  PREPARATION 
OF  SAUERKRAUT  AND  PICKLES 

Materials. — Cabbage  25  pounds  and  cucumbers  30  pounds. 

Procedure . 

1.  Sauerkraut. — Select  only  mature  sound  heads  of  cabbage. 

A.  Preparation. — Cut  in  quarters  and  remove  the  core.     Shred  by 
hand  with  a  large  knife  or  by  means  of  a  vegetable  slicer. 

B.  Salting. — Mix  the  shredded  cabbage  thoroughly  with  fine  salt  at 
the  rate  of  2  ounces  (about  60  grams)  of  salt  for  each  5  pounds  of  cab- 
bage.    Pack  firmly,  but  not  too  tightly,  in  a  3-gallon  stoneware  crock. 
Cover  with  a  clean  table-plate  or  circular  piece  of  board  slightly  smaller 
in  diameter  than  the  crock.    Place  a  heavy  weight  on  the  cover  so  that 
after  24  hours  the  level  of  the  brine  formed  by  the  salt  and  cabbage 
juice  is  above  the  cover.    Do  not  use  lime  stone. 

C.  Fermentation. — Place  the  crock  in  a  warm  room  or  in  an  incu- 
bator, preferably  at  about  86°F.     Remove  scum  occasionally.     When 
fermentation  is  complete,  usually  6  to  8  days,  determine  the  acidity  of 
the  brine  by  titration  of  a   10-c.c.   sample   as   directed   in   Appendix, 
page  98. 

D.  Canning. — Fill  two  glass-top  fruit-jars  completely  with  the  fin- 
ished sauerkraut;  add  brine  from  the  fermentation  crock  to  fill  the  jars 
to  overflowing.    Seal  and  store  without  sterilization. 

Place  the  remainder  of  the  kraut  into  cans,  completely  full.  Add 
brine  from  the  fermentation  crock  to  fill  the  cans  completely,  or  if  there 
is  insufficient  fermented  brine,  add  a  3  per  cent,  brine.  Exhaust  5 
minutes  in  live  steam,  seal  and  sterilize  25  minutes  in  boiling  water. 
Store  and  compare  with  unsterilized  samples  after  one  month. 

2.  Salt  Pickles. — A.  Preparation. — Wash   the   fresh   cucumbers    and 
place  about  12  pounds  in  a  4-gallon  crock.     Cover  with  a  10  per  cent, 
brine  (40°  salometer).    Cover  as  directed  for  sauerkraut  and  weight  the 
cover  sufficiently  to  keep  the  cucumbers  submerged  in  the  brine. 

B.  Fermentation. — Store  at  room  temperature.  At  weekly  intervals 
for  a  period  of  6  weeks  place  y±  pound  of  salt  on  the  cover  for  each  6 
quarts  of  brine.  Salt  placed  on  the  cover  dissolves  gradually  and  is 
distributed  evenly  in  the  brine.  The  surface  of  the  brine  must  be 
skimmed  occasionally  to  prevent  putrefaction  and  loss  of  acid.  When 

86 


FRUIT  AND  VEGETABLE  PRODUCTS  87 

the  curing  process  is  complete  the  cucumbers  should  be  firm  in  texture 
and  should  have  changed  in  appearance  from  opaque  white  to  trans- 
lucent. The  bright  green  color  of  the  fresh  cucumbers  becomes  an  olive 
green.  Six  to  eight  weeks  are  usually  required  for  proper  curing.  Cu- 
cumbers in  this  condition  are  known  as  "salt  stock"  and  are  used  in  the 
preparation  of  sour  or  sweet  pickles  as  directed  in  Assignment  XXXI 
3  and  4.  Salt  stock  will  keep  indefinitely  if  the  brine  is  skimmed  fre- 
quently to  prevent  excessive  growth  of  film  yeast. 

3.  Processing  Salt  Pickles. — A.  Removal  of  Salt. — Place  the  salted 
cucumbers  from  Section  2  in  a  large  pot.     Cover  with  water  at  about 
120°F.    Place  the  pot  on  a  hot  plate  and  maintain  at  this  temperature 
for  10  to  12  hours.     Repeat  this  extraction  until  most  of  the  salt  is 
removed  as  indicated  by  the  taste. 

B.  Grading. — Grade  the  cucumbers  into  two  sizes.  Use  the  large 
size  for  sour  pickles  and  reserve  the  small  size  for  sweet  pickles. 

4.  Sour  Pickles. — A.  Addition  of  Vinegar. — Cover  the  large  pickles 
from  Assignment  XXXI  3  with  distilled  vinegar  of  4  to  6  per  cent,  acetic 
acid.     Allow   to   stand   until   the   vinegar    has    penetrated   the    pickles 
thoroughly. 

B.  Canning. — Fill  one  glass  jar  with  tne  pickles  and  vinegar.  Seal 
but  do  not  sterilize. 

Put  the  remainder  of  the  pickles  into  double-lacquered  cans.  The 
cans  should  be  filled  completely  with  vinegar.  Exhaust  in  live  steam 
J2  to  15  minutes.  Seal  hot.  No  further  sterilization  is  required. 

5.  Sweet    Pickles. — A.    Preliminary    Treatment. — Cover    the    small 
pickles  from  Assignment  XXXI  3  with  distilled  vinegar  containing  4  to 
4y»  per  cent,  acetic  acid  and  allow  to  stand  about  10  days.     Drain  the 
vinegar  and  in  it  dissolve  3  pounds  of  sugar  per  gallon,  in  which  immerse 
the  pickles  again  for  about  one  week. 

B.  Addition  of  Spices. — Remove  the  vinegar  and  add  about  20  grams 
of  mixed  whole  spices  (obtainable  from  any  grocery  store)  per  gallon. 
The  spices  most  commonly  used  are  black  pepper,  cayenne  pepper,  cloves, 
cinnamon,  celery  seed,  caraway  seed,  dill  seed,  mustard,  allspice,  carda- 
mom, bay  leaves  and  coriander.  Heat  to  the  simmering  point  for  about 
Vi>  hour.  Add  fresh  vinegar  to  replace  that  lost  by  evaporation,  strain 
out  the  spices,  and  add  sugar  at  the  rate  of  3  pounds  per  gallon.  Cover 
the  pickles  with  the  spiced  vinegar  and  allow  to  stand  about  one  week. 
Can  as  directed  in  Assignment  XXXI  4. 

6.  Dill  Pickles. — Select  and  wash  large  fresh  cucumbers  uniform  in 
size. 

A.  Packing. — Place  a  layer  of  dill  herb  and  V-j  ounce  of  mixed  dill 
pickle  spices  in  the  bottom  of  a  4-gallon  crock.  Fill  the  crock  within 
2  or  3  inches  of  top  and  add  another  layer  of  dill  and  Vi>  ounce  of  spices 


88  LABORATORY  MANUAL 

B.  Brining. — Cover  with  a  brine  consisting  of  1  pound  of  salt  and 
iy2  pints  of  vinegar  to  2M>  gallons  of  water.     Cover  with  a  weighted 
plate  or  board. 

C.  Fermentation. — Store  at  a  temperature  of  about  86°F.  and  skim 
occasionally.    Fermentation  should  be  complete  within  10  to  14  days. 

4.  Canning. — Can  as  directed  in  Assignment  XXXI  4. 

Suggestions. — Small  (pearl)  onions,  cauliflower,  green  tomatoes,  and 
string  beans  are  prepared  for  pickling  by  6  to  8  weeks'  storage  in  brine 
strong  enough  (15  per  cent,  salt)  to  prevent  fermentation.  They  may 
then  be  converted  into  sour  or  sweet  pickles  as  directed  in  Assignment 
XXXI  4  and  5  and  mixed  in  any  desired  proportion  with  cucumber  pickles. 


ASSIGNMENT  XXXIL— PRACTICE  IN  THE  PREPARATION 

OF  FRUIT  ACIDS 

Materials. — Twenty-five  pounds  of  lemon  or  lime  culls.  One-half 
pound  of  crude  grape  argol;  i.  e.,  crystalline  sediment  from  grape  juice 
or  wine. 

Procedure : 

1.  Citric  Acid. — A.  Extraction  of  Juice. — Crush  and  press  the  juice 
from  25  pounds  of  lemon  culls.  To  the  pomace  add  4,000  c.c.  of  water. 
Mix  well;  press  a  second  time.  Mix  the  liquids  from  the  two  pressings. 
Weigh  the  pomace  and  measure  the  volume  of  the  combined  extracts. 

B.  Fermentation. — Place  the  juice  in  a  stoneware  crock  and  add  a 
cake  of  compressed  yeast.     Mix  the  yeast  thoroughly  with  the  juice. 
Cover  with  a  cloth  and  allow  to  ferment  at  room  temperature  one  week. 

C.  Filtration. — Add  2  grams  of  finely  pulverized  "Filter  Cel"  per 
100  c.c.  of  fermented  juice  and  bring  to  boiling.     Allow  to  settle  for 
24  hours.    Decant  off  the  clear  liquid  and  filter  if  necessary.    Filter  the 
cloudy  liquid  and  sediment  through  coarse  filter  paper  and  combine  the 
clear  liquids.     Measure  the  volume. 

D.  Neutralization. — Determine  the  percentage  of  citric  acid  in  the 
juice  by  titration  as  directed  in  Appendix,  page  98.     Calculate  from  the 
following  reaction  the  amount  of  precipitated  chalk  (calcium  carbonate) 
required  to  neutralize  the  acid,  and  add  5  per  cent,  in  excess  to  the  liquid. 

Citric  Acid+Calcium  Carbonate  =  Calcium  Citrate + Water     +Carbon  Dioxide 
2CJI8O7      +3CaCO3  =Cas(C,H8O7)2      +3H2O      +3CO2 

384  Cms.    +300  Cms.  =474  Cms.  +54  Cms. +  132  Cms. 

Mix  well.  Boil  until  evolution  of  carbon  dioxide  gas  ceases.  Filter 
through  filter  paper  while  still  boiling  hot.  Wash  the  precipitate  on  the 
filter  with  a  small  amount  of  boiling  water. 

E.  Decomposition  of  Calcium  Citrate. — Transfer  the  precipitate  to 
a  large  beaker  and  add  sufficient  water  to  make  a  thin  paste. 

Add  sulphuric  acid  (20  per  cent,  solution)  slowly  with  constant  stir- 
ring until  a  drop  of  the  liquid  placed  on  a  piece  of  methyl  violet  indicator 
paper  changes  the  color  of  the  indicator  to  blue.  To  prepare  the  indi- 
cator paper  dip  small  strips  of  filter  paper  in  dilute  methyl  violet  solution 
and  allow  to  dry  at  room  temperature. 

F.  Filtration. — Filter  through   filter  paper  to  remove   calcium   sul- 
phate.   Wash  precipitate  with  a  small  amount  of  cold  water. 

89 


90  LABORATORY  MANUAL  OF 

G.  Concentration. — Place  the  filtrate  in  a  large,  heavy-walled  flask 
connected  to  a  condenser  and  vacuum  pump.  Concentrate  by  boiling  in 
vacua  to  a  density  of  20°  to  25°  Baume  (test  made  at  50°C.).  Transfer 
to  a  large  beaker  and  allow  to  cool  to  room  temperature  and  settle.  Filter 
off  the  precipitated  calcium  sulphate  and  return  the  filtrate  to  the 
vacuum  flask.  Concentrate  in  vacuo  to  37°  to  39°  Baume  (test  made  at 
50°C.). 

H.  Crystallization. — Transfer  the  liquor  to  a  heavy-walled  beaker 
or  small  stoneware  jar  and  allow  to  cool  and  crystallize  for  one  week. 
Stir  two  or  three  times  daily. 

1.  Separation  from  Mother  Liquor. — Separate  the  crystals  from  the 
mother  liquor  by  draining  through  cloth.    This  gives  "brown  crystals." 
The  mother  liquor  still  contains  recoverable  citric  acid,  but  in  this  assign- 
ment may  be  neglected  and  the  mother  liquor  discarded. 

J.  Decolorization. — Dissolve  the  drained  crystals  in  a  small  amount 
of  distilled  water  and  dilute  to  20°  to  25°  Baume.  Add  3  per  cent,  by 
weight  of  finely  ground  vegetable  decolorizing  carbon  such  as  "Noirit" 
or  "Eponit."  Stir  and  heat  to  boiling.  Filter  free  of  carbon.  A  water- 
white  filtrate  should  be  obtained.  Wash  the  carbon  on  the  filter  with  a 
small  amount  of  hot  water  and  combine  the  filtrates. 

K.  Concentration  of  decolorized  liquor. — Concentrate  in  vacuo  to 
36°  to  37°  Baume  (test  made  at  50°C.)  and  allow  to  crystallize  as  di- 
rected in  Assignment  XXXII  1-7. 

L.  Drying. — Separate  the  crystals  from  the  mother  liquor  and  allow 
to  dry  in  the  air  several  days.  Weigh  and  calculate  the  yield  of  citric 
acid  in  pounds  per  ton  of  fresh  fruit.  The  mother  liquor  contains  re- 
coverable citric  acid  but  in  this  assignment  may  be  discarded. 

2.  Cream  oj  Tartar. — A.  Dissolving  Cream  of  Tartar. — Weigh  200 
grams  of  finely  ground  crude  "argol"  and  mix  with  about  5,000  c.c.  of 
distilled  water.     Boil  10  minutes  and  filter  through  cloth  until  fairly 
clear. 

B.  Concentration. — Concentrate  by  boiling  to  about  1,000  c.c. 

C.  Crystallizing. — Set  aside  in  a  cool  place  and  allow  to  crystallize 
for  4  to  5  days.     Separate  crystals  from  mother  liquor  by  decantation. 

Concentrate  the  mother  liquor  in  vacuo  to  about  200  c.c.  and  allow 
to  crystallize  as  above.  Combine  the  two  lots  of  crystals  and  discard 
the  mother  liquor. 

D.  Decolorizing. — Dissolve  the  crystals  in  about  5,000  c.c.  of  water 
and  add  1  per  cent,  by  weight  of  vegetable  decolorizing  carbon.    Boil  5 
minutes  and  filter  through  paper. 

E.  Concentration  and  Crystallizing. — Concentrate  in  vacuo  to  about 
1,000  c.c.    Pour  into  a  beaker  and  allow  to  crystallize  several  days.    Re- 
move the  mother  liquor  and  dry  the  crystals  in  the  air.    Concentrate  the 


FRUIT  AND  VEGETABLE  PRODUCTS  91 

mother  liquor  to  about  200  c.c.,  crystallize;  separate  the  crystals  and  dry 
in  the  air.  Weigh  the  air-dry  crystals  from  both  lots  and  calculate  the 
total  yield  in  percentage. 

Suggestions: 

1.  Tartaric  acid  may  be  prepared  from  the  crude  argol  or  cream  of 
tartar  in  a  method  analogous  to  that  for  citric  acid. 

2.  Tartaric  acid  may  be  prepared  synthetically  from  carbon  dioxide 
and  water  by  a  patented  electrolytic  process. 

3.  Crude  argol  may  be  obtained  from  any  grape-juice  factory  or 
cream-of -tartar  refinery. 


ASSIGNMENT   XXXIIL— PRACTICE   IN   OLIVE   PICKLING 

Materials. — Thirty-five  pounds  of  ripe  olives  of  a  commercial  variety 
such  as  Mission,  Manzanillo  or  Sevillano.  Ten  pounds  of  green  olives, 
preferably  Sevillano  or  Manzanillo. 

Procedure : 

1.  Grading. — Grade  the  olives  by  screens  or  by  hand,  as  suggested  in 
Table  XII.    Record  the  weight  of  each  size. 

2.  Storage. — If  the  olives  can  not  be  pickled  immediately  after  grad- 
ing place  them  in  a  brine  of  10  per  cent.  salt.    Store  in  a  cool  place.    If 
the  olives  float,  place  a  weight  upon  them  to  hold  them  beneath  the 
surface;  or  seal  in  glass  jars.     Olives  after  storage  in  brine  must  be 
soaked  in  several  changes  of  water  for  24  hours  before  pickling. 

3.  Pickling  Ripe  Olives  by  Usual  Commercial  Process. — A.  First  Lye. 
— Prepare  a  lye    (sodium  hydroxide)    solution  containing   for  Mission 
olives  2  per  cent,  sodium  hydroxide  and  for  Manzanillo  and  Sevillano 
varieties  iy2  per  cent.    Cover  the  olives  in  a  crock  with  this  solution  at 
a  temperature  of  65°  to  75°F.    Allow  to  remain  until  the  lye  has  barely 
penetrated  the  skin  of  the  fruit  as  evidenced  by  discoloration  of  the  skin 
and  flesh.     It  should  not  be  allowed  to  penetrate  more  than  1/16  inch 
into  the  flesh.    This  will,  at  the  temperature  given  above,  usually  require 
3  to  5  hours.    Discard  the  lye. 

B.  First  Exposure. — Allow  the  olives  to  remain  exposed  to  the  air 
until  an  even  black  color  is  obtained.    Stir  the  olives  at  least  three  times 
daily.    Three  to  five  days'  time  will  be  required. 

C.  Subsequent  Lye   Treatments   and   Exposures. — Cover  the   olives 
with  a  0.5  per  cent,  lye  solution  and  allow  to  penetrate  about  one-fourth 
way  to  the  pit.    A  drop  of  phenolphthalein  indicator  placed  on  the  cut 
surface  of  the  fruit  will  indicate  the  depth  of  penetration  of  the  lye. 
Remove  and  discard  the  lye.     Expose  the  olives  to  the  air  24  hours. 
Cover  again  with  a  0.5  per  cent,  lye  solution  and  allow  to  penetrate  about 
%  to  pit.    Remove  and  discard  the  lye.    Expose  the  olives  again  to  the 
air  for  24  hours.    Cover  the  olives  again  with  a  0.5  per  cent,  lye  solution 
and  allow  it  to  penetrate  completely  to  the  pit.     Remove  and  discard 
the  lye.    Expose  the  fruit  again  for  24  hours  to  the  air. 

D.  Washing. — Cover  the  olives  with  water  and  change  the  water 
twice  or  three  times  daily  until  all  lye  is  removed  from  the  flesh  of  the 

92 


FRUIT  AND  VEGETABLE  PRODUCTS  93 

fruit.     (This  is  determined  by  applying  a  drop  of  phenolphthalein  to  the 
cut  surface;  or  by  taste). 

E.  Brining. — Place  the  olives  in  a  3  per  cent,  salt  brine  for  two  days. 

F.  Filling  and  Exhausting. — Fill  cans  with  the  olives,  after  careful 
sorting.    Add  hot  3  per  cent,  brine  and  exhaust  in  steam  for  6  minutes. 

G.  Sterilization. — Seal   and   sterilize   in   a   retort   at   240 °F.    for   40 
minutes. 

4.  Pickling  Ripe  Olives   by  the  Aerated  Water  Process. — Put  ripe 
olives  in  a  -3-gallon  stoneware  crock  until  about  two-thirds  full.     Cover 
with  a  iy2  per  cent,  lye   (sodium  hydroxide)   solution.     Insert  a  glass 
tube  to  the  bottom  of  the  container  and  connect  the  tube  to  a  supply  of 
compressed  air.    Pass  air  through  the  liquid  vigorously  until  the  lye  has 
penetrated  the  skin  of  the  olives  and  has  entered  the  flesh  of  the  olives 
to  a  depth  of  1/32  inch.     Remove  the  lye  and  replace  it  with  water. 
Continue  the  aeration  of  the  liquid,  changing  the  water  twice  daily.    At 
the  end  of  two  days  cover  the  olives  with  a  %  per  cent,  lye  solution 
and  allow  it  to  penetrate  about  one-half  way  to  the  pit,  aerating  the 
liquid  continuously  during  this  treatment.     Replace  the   lye  solution 
with  water  and  continue  the  aeration  for  another  24  hours.    Again  add 
a  ^  per  cent,  lye  solution  and  allow  it  to  penetrate  nearly  to  the  pits  of 
the  fruit.  Replace  it  with  water  for  24  hours.  Finally  place  a  ^  per  cent, 
lye  solution  on  the  olives  and  allow  it  to  penetrate  to  the  pit.    Replace 
the  lye  with  water,  which  should  be  changed  twice  daily  until  the  olives 
are  free  from  lye.    Cover  the  olives  with  a  3  per  cent,  salt  solution  and 
allow  them  to  stand  24  hours.     During  all  lye,  water  and  brine  treat- 
ments continue  the  aerating  process.    Can  and  sterilize  the  pickled  olives 
as  directed  in  Assignment  XXXIII  3.     Compare  the  flavor  and  general 
quality  with  the  olives  from  Assignment  XXXIII  3. 

5.  Pickling  Ripe  Olives  by  the  Greek  Process. — Use  large  thoroughly 
ripe  olives.     Mix  the  olives  with  one-fourth  their  weight  of  coarsely 
crushed  rock-salt  in  a  wooden  box  equipped  with  a  perforated  bottom  to 
permit  escape  of  brine  formed  during  pickling.    Cover  the  olives  with  a 
layer  of  crushed  rock-salt  about  */£  inch  thick,  this  salt  being  in  addition 
to  that  mixed  with  the  fruit  as  directed  above.     Allow  the  mixture  of 
olives  and  salt  to  stand  in  a  cool  place  until  the  fruit  has  developed  the 
characteristic  wrinkled  appearance  of  commercial  Greek  olives  and  until 
most  of  the  bitterness  has  disappeared.     The  time  usually  required  is 
about  G  weeks.    The  salt  and  olives  should  be  thoroughly  mixed  once  a 
week  during  the  curing  period.     Pack  the  finished  product  in  jars  or 
small  wooden  boxes  with  about  10  per  cent,  of  its  weight  of  coarsely 
crushed  rock-salt. 

6.  Green  Olives   by  Fermentation  Process. — Use   hard   green  olives 
which  have  attained  full  size.    The  Sevillano  olive  is  best  for  the  prepa- 


LABORATORY  MANUAL 


ration  of  green  olive  pickles.  Cover  the  olives  in  a  stoneware  crock  with 
a  11/2  per  cent,  lye  solution  (sodium  hydroxide).  Allow  the  lye  to  pene- 
trate about  three- fourths  the  distance  to  the  pits  of  the  fruit.  Remove 
and  discard  the  lye.  Cover  the  olives  immediately  with  water  twice 
daily  until  the  fruit  is  free  from  lye.  Place  the  olives  in  a  small  wooden 
keg  or  wooden  pickle  bucket  of  convenient  size  or  in  a  large  fruit  jar. 
Fill  the  container  completely  with  a  brine  of  9  per  cent,  salt  and  con- 
taining 1/10  of  1  per  cent,  acetic  acid  from  vinegar.  Seal  and  set  aside 
at  room  temperature  until  the  olives  have  developed  the  flavor  desired. 
Two  to  three  months'  time  will  usually  be  sufficient  for  the  completion 
of  the  necessary  lactic  acid  fermentation. 

Suggestions. — The  relation  of  the  diameter  of  olives  to  the  commer- 
cial size  grades  is  shown  by  the  following  table: 

TABLE  XII. — RELATION  OF  SIZE  GRADES  AND  DIAMETER  OF  RIPE  OLIVES 


Grade 

Number 
Per  Pound* 

Diameter  in 
Inches 

Grade 

Number 
Per  Pound* 

Diameter  in 
Inches 

Small  

120-135 

9/16 

Mammoth  . 

65-75 

13/16 

Medium  

105-120 

10/16 

Giant  

55-65 

14/16 

Large  

90-105 

11/16 

Jumbo  

45-55 

15/16 

Extra  Large  .  .  . 

75-  90 

12/16 

Colossal.  .  .  . 

35-45 

16/16 

*  The  relatively  wide  range  in  "number  per  pound"  is  necessary  to  include  all 
varieties  of  olives  of  different  shapes. 


ASSIGNMENT  XXXIV.— PRACTICE  IN  THE  PREPARA- 
TION OF  MUSEUM  SPECIMENS 

Materials. — Freshly  gathered  specimens  of  fruits  and  vegetables  as 
perfect  in  shape,  color  and  condition  as  possible.  Perfect  specimens  of 
large  size  and  free  from  blemishes  give  the  best  results. 

Procedure: 

1.  Green  Colored  Products   (such  as  artichokes,  string  beans,  peas, 
spinach,  green  leaves,  cucumbers,  green  almonds,  and  hard  green  fruits). 
The  preservation  of  the  green  color  (chlorophyll)  of  plant  tissues  depends 
upon  fixation  of  the  color  with  copper  salts. 

A.  Fixation  of  Chlorophyll  Color. — Immerse  in  a  5  per  cent,  copper 
sulphate  solution  until  the  color  has  been  fixed  as  indicated  by  a  definite 
deepening  of  the  tint.    This  will  require  24  hours  or  less. 

B.  Storage  Solution. — Remove  the  specimens  from  the  copper  sul- 
phate solution,  rinse  in  running  water  for  2  to  3  hours  to  remove  excess 
copper  sulphate.    Rinse  in  distilled  water  and  store  in  a  glass  jar  filled 
with  a  solution  containing  1  ounce  of  6  per  cent,  sulphurous  acid  per 
gallon  of  distilled  water.    The  jar  should  be  well  sealed  to  prevent  loss 
of  the  sulphurous  acid  and  the  solution  renewed  once  every  6  months. 

2.  Tomatoes  and  Red  Peppers. — Store  specimens  of  uniform  red  color 
and  firm  texture  in  the  following  solution: 

Distilled  water.  ...      1  gallon  Sulphurous  acid  6  per  cent,  solution.  .1/8  ounce 

Salt 2  ounces  Potassium  nitrate 1/4  ounces 

Formalin 1/4  ounce  Glycerine 8  ounces 

Green  leaves  should  be  fixed  separately  in  5  per  cent,  copper  sulphate 
solution  before  placing  in  the  above  solution. 

3.  White  Vegetables  (corn  on  cob,  cauliflower,  asparagus,  dry  onions, 
celery,  turnips,  summer  squash,  etc.)  can  be  preserved  in  the  following 
solution: 

Distilled  water 1  gallon  Potassium  nitrate.  ...  1  ounce 

Sulphurous  acid  6  per  cent,  solution ...  1  ounce  Salt 3  ounce 

Copper  sulphate  to  give  a  faint  green  solution. 

4.  Citrus  Fruits  (oranges,  grapefruit,  lemons,  and  limes)  retain  their 
color  and  form  satisfactorily  in  the  following  solution: 

Water 1  gallon  Sulphurous  acid  6  per  cent,  solution 1/2  ounce 

Formalin 1/8  ounce  Boric  acid 1  ounce 

Copper  sulphate  to  give  a  faint  green  solution. 
95 


96  LABORATORY  MANUAL 

5.  White  Grapes,  Ripe  Pears  and  Yellow  Apples. — Store  in  the  fol- 
lowing solution.    No  preliminary  fixation  of  color  is  necessary. 

Distilled  water 1  gallon  Boric  acid 1  ounce 

Potassium  nitrate 1/8  ounce  Glycerine 6  ounces 

Copper  sulphate  to  give  a  faint  green  solution. 

6.  Black  Grapes  and  Other  Black  Fruits  (such  as  ripe  prunes,  Damson 
plums,  black  cherries,  etc.). — Store  in  the  following  solution.     No  pre- 
liminary fixation  of  color  is  necessary. 

Distilled  water 1  gallon  Boric  acid 1  1/2  ounces 

Formalin 3  ounces  Salt  (Na  Cl) 3  ounces 

Glycerine 6  ounces 

7.  Berries,  Peaches,  Apricots,  Red  or  White  Cherries,  Red  Grapes  and 
Other  Red  Fruits. — Fix  the  color  in  the  following  solution  until  the  red 
color  has  changed  to  a  uniform  purple,  but  do  not  prolong  the  treatment 
beyond  this  point;  24  to  36  hours  is  usually  sufficient. 

Distilled  water 1  gallon  Formalin 1/2  ounce 

Sulphurous  acid  6  per  cent,  solution 1  ounce  Glycerin 10  ounces 

When  the  color  has  been  fixed,  store  the  specimens  in  the  following 
solution : 

Distilled  water 1  gallon  Sulphurous  acid  6  per  cent,  solution 1  ounce 

.  Renew  this  solution  once  each  6  months. 

Suggestions: 

1.  Except  with  specimens  of  green  color,  leaves  should  be  fixed  sepa- 
rately from  the  fruit  specimens  in  5  per  cent,  copper  sulphate  solution. 
The  fruit  after  fixation  in  a  suitable  solution  can  be  tied  to  the  branches 
by  means  of  thread.     Delicately  tinted  fruits  if  placed  in  5  per  cent, 
copper  sulphate  solution  usually  develop  an  undesirable  brown  color,  and 
green  leaves  if  placed  directly  in  the  solutions  used  for  fruits  either 
become  brown  in  color  or  bleached. 

2.  In  all  cases  where  glycerine  is  recommended,  it  may  be  replaced 
by  cane  sugar  to  increase  the  Balling  degree  of  the  liquid  to  approxi- 
mately that  of  the  juice  of  the  fruit.    For  grapes  this  is  about  20°  to  22° 
Balling  and  for  most  other  fruits  12°  to  15°  Balling. 


METHODS  OF  ANALYSIS 

1.  Preparation  of  Standard  Acid  and  Alkali  Solutions: 

A.  Tenth-normal  Hydrochloric  Acid. — Dilute  8.6  c.c.  of  concentrated 
hydrochloric  acid  C.P.  to  1,000  c.c.  with  distilled  water  in  a  volumetric 
flask. 

Weigh  exactly  2.6500  grams  of  anhydrous  sodium  carbonate  C.P.  in 
a  small  beaker  and  wash  into  a  500-c.c.  volumetric  flask  with  distilled 
water  and  dilute  to  exactly  500  c.c.  Mix  thoroughly.  The  distilled  water 
should  be  freed  from  carbon  dioxide  by  previous  boiling  and  cooling. 

Pipette  exactly  20  c.c.  of  this  N/10  sodium  carbonate  solution  into 
a  beaker  or  flask,  add  a  few  drops  of  methyl  orange  indicator  (0.2  grams 
in  500  c.c.  of  distilled  water),  and  titrate  with  the  approximately  N/10 
hydrochloric  acid  measured  from  a  burette  until  the  color  suddenly 
changes  from  yellow  to  orange. 

If  less  than  20  c.c.  of  the  acid  are  required  to  neutralize  20  c.c.  of 
the  N/10  sodium  carbonate,  the  acid  is  stronger  than  N/10  and  should 
be  diluted  with  sufficient  distilled  water  to  reduce  its  strength  to  ex- 
actly N/10. 

Example. — If  18.9  c.c.  of  the  hydrochloric  acid  neutralized  20  c.c. 
N/10  sodium  carbonate  and  945  c.c.  of  the  acid  remained  for  dilution 

945 

^— -X(20.0  —  18.9)  =  55  c.c.  of  water  required  to  dilute  the  hydro- 
18.9 

chloric  acid  to  N/10.    The  strength  of  the  acid  adjusted  to  N/10  should 
be  checked  by  a  second  titration  against  the  N/10  sodium  carbonate. 

B.  Tenth-normal   Sodium    Hydroxide. — Dissolve   4.5   grains   of   dry 
sodium  hydroxide  C.P.  in  distilled  water  free  of  carbon  dioxide  and 
dilute  to  1,000  c.c. 

Pipette  exactly  20  c.c.  of  this  solution  into  a  beaker  or  flask,  add  a 
few  drops  of  methyl  orange  and  titrate  with  the  N/10  hydrochloric  acid 
as  in  A  above. 

If  more  than  20  c.c.  of  N/10  hydrochloric  acid  are  required,  the 
sodium  hydroxide  is  stronger  than  N/10  and  should  be  diluted  with  dis- 
tilled water  to  reduce  its  strength  to  N/10. 

Example. — If  21.1  c.c.  of  N/10  hydrochloric  acid  were  required  to 
neutralize  20  c.c.  of  the  sodium  hydroxide  and  980  c.c.  of  the  alkali 

remained  for  dilution^-  x  (21.1  —  20.0)  =  53.9  c.c.  of  water  required 

to  dilute  the  alkali  to  exactly  N/10.    Check  the  adjusted  solution  by  a 
second  titration  against  N/10  hydrochloric  acid. 

97 


98  LABORATORY  MANUAL  OF 

2.  Determination  of  Acidity. — Pipette  exactly  10  c.c.  of  fruit  or 
other  juice  into  a  flask  or  beaker,  add  50  to  100  c.c.  distilled  water  and 
severs!  drops  of  phenolphthalein  (2  grams  in  1,000  c.c.  of  50  per  cent, 
alcohol)  and  titrate  with  N/10  sodium  hydroxide  until  a  permanent  pink 
color  is  obtained. 

Highly  colored  samples,  such  as  grape  juice,  must  be  diluted  to  500 
c.c.  or  more  and  more  indicator  added  in  order  that  the  color  of  the 
sample  will  not  mask  the  end  point  of  the  titration. 

In  the  case  of  strongly  acid  products,  such  as  lemon  juice  or  vinegar, 
10  c.c.  should  be  diluted  to  100  c.c.  with  distilled  water  in  a  volumetric 
flask.  After  thorough  mixing,  withdraw  10  c.c.  for  determination  of  acid- 
ity, multiplying  the  result  by  10. 

Factors. — One  c.c.  of  N/10  sodium  hydroxide  will  neutralize  the  fol- 
lowing equivalents  of  acid: 

Acetic  acid 0060  grams  Tartaric  acid 0075  grams 

Citric  acid 0064  grams  Lactic  acid 0090  grams 

Malic  acid 0067  grams  Oleic  acid 0282  grams 

3.  Determination  of  Alkalinity. — The  alkalinity  of  commercial  lye 
can  be  determined  by  weighing  exactly  4.000  grams  of  a.  representative 
sample  into  a  dry  beaker.    The  sample  should  be  weighed  as  quickly  as 
possible  to  avoid  absorption  of  moisture  from  the  air.    Wash  the  sample 
into  a  1,000-c.c.  volumetric  flask  and  dilute  to  the  mark  with  distilled 
water.     Mix  thoroughly  and  titrate  exactly  20  c.c.  with  N/10  hydro- 
chloric acid,  using  phenolphthalein  indicator.     Since  1  c.c.  N/10  hydro- 
chloric acid  neutralizes  .004  grams  of  sodium  hydroxide,  if  the  above 
directions  are  followed,  each  c.c.  of  acid  required  is  equivalent  to  5  per 
cent,  sodium  hydroxide  in  the  original  sample. 

4.  Preparation  of  Standard  Silver  Nitrate  Solution. — Weigh  ex- 
actly 8.495  grams  dry  C.P.  silver  nitrate  into  a  small  beaker.    Wash  into 
a  500-c.c.  volumetric  flask  with  distilled  water  and  dilute  to  500  c.c. 

If  C.P.  silver  nitrate  previously  dried  three  hours  at  100°C.  is  em- 
ployed, standardization  of  the  solution  is  not  necessary.  The  normality 
of  the  silver  nitrate  may  be  verified  as  follows:  Pipette  20  c.c.  of  N/10 
hydrochloric  acid  into  a  beaker  or  flask;  add  a  few  c.c.  of  chromate 
indicator  (5  grams  potassium  chromate  in  100  c.c.  distilled  water)  and 
titrate  until  the  lemon-yellow  color  changes  to  a  deeper  orange  color. 
Do  not  continue  till  a  brick-red  color  is  obtained.  Exactly  20  c.c.  of  the 
silver  nitrate  solution  should  be  required  for  this  titration. 

5.  Determination  of  Sodium  Chloride  in  Brine. — Pipette  10  c.c.  of 
the  sample  into  a  100-c.c.  volumetric  flask.     Dilute  to  the  mark  with 
distilled  water  and  mix  thoroughly. 

Pipette  20  c.c.  of  the  diluted  sample  into  a  beaker  or  flask,  add  about 


FRUIT  AND  VEGETABLE  PRODUCTS  99 

25  c.c.  of  distilled  water  and  a  few  c.c.  of  chromate  indicator,  and  titrate 
as  described  in  4. 

One  c.c.  N/10  silver  nitrate  is  equivalent  to  .00585  grams  of  sodium 
chloride.  If  the  above  directions  are  followed  each  c.c.  of  N/10  silver 
nitrate  equals  0.29  per  cent,  sodium  chloride  in  the  original  sample. 

6.  Preparation  of  Standard  Iodine  and  Thiosulphate  Solutions: 

A.  N/20    Iodine. — Weigh    exactly    6.346   grams   of    sublimed    iodine 
crystals  into  a  small  beaker.    Add  about  10  to  15  grams  of  C.P.  potas- 
sium iodide  and  a  small  amount  of  distilled  water.    Stir  till  the  iodine  is 
dissolved,  wash  into  a  1,000-c.c.  volumetric  flask  and  dilute  to  the  mark 
with  distilled  water. 

B.  N/20  Sodium  Thiosulphate. — Weigh  exactly  12.41  grams  of  C.P. 
sodium  thiosulphate  (Na2S2O3.  5H2O)  into  a  small  beaker;  dissolve  in 
distilled  water;  wash  into  a  1,000-c.c.  volumetric  flask  and  dilute  to 
the  mark. 

C.  Standardization. — Weigh  exactly  2.4516  grams  of  C.P.  potassium 
dichromate  into  a  small  beaker.     Dissolve  and  wash  into  a  1,000-c.c. 
volumetric  flask.    Dilute  to  mark  with  distilled  water.    Prepare  a  solu- 
tion containing  approximately   10  grams  of  C.P.   potassium  iodide  in 
100  c.c.  of  distilled  water. 

Place  10  c.c.  of  this  potassium  iodide  solution  and  50  c.c.  of  distilled 
water  in  a  200-c.c.  Erlenmeyer  flask.  Add  5  c.c.  concentrated  hydro- 
chloric acid,  and  exactly  20  c.c.  of  the  N/20  dichromate  solution.  Add 
a  few  drops  of  starch  indicator  (prepared  by  boiling  1  gram  of  starch 
in  100  c.c.  distilled  water  and  preserving  with  a  few  drops  of  chloroform). 
Titrate  with  the  sodium  thiosulphate  solution  until  the  blue  color  just 
disappears. 

Since  20  c.c.  of  the  N/20  potassium  dichromate  solution  was  used, 
20  c.c.  of  the  thiosulphate  solution  should  be  required  to  react  with  the 
iodine  liberated  by  the  dichromate  from  the  potassium  iodide  solution. 
The  normality  of  the  thiosulphate  solution  can  be  determined  by  dividing 
20  by  the  c.c.  of  thiosulphate  solution  used,  and  multiplying  by  .05. 
Example:  21 A  c.c.  of  thiosulphate  used. 

on 
Normality  =  2j4X. 05  =  .0467  N. 

To  determine  the  normality  of  the  iodine  solution  proceed  as  follows: 
Pipette  20  c.c.  of  the  iodine  solution  into  a  flask  or  beaker.  Add  a  few 
drops  of  starch  indicator  and  titrate  witli  thiosulphate  solution  till  the 
blue  color  just  disappears.  The  normality  of  the  iodine  is  then  obtained 
from  the  following  formula: 

c.c.  thiosulphate  usr<l 

'  X  normality  of  thiosulphate  sol. 


100  LABORATORY  MANUAL  OF 

Example:  Thiosulphate  solution  used  =  21.3  c.c. 

21  3 

Normality  of  iodine  solution  =  -^-  X  0.467  =  .04973  N 

zo 

7.  Approximate  Determination  of  Total  Sulphurous  Acid: 

A.  Place  50  grams  of  finely  ground  dried  fruit,  or  other  sample,  in 
a  500-c.c.  distillation  flask.    Add  about  300  c.c.  of  distilled  water  and 
5  c.c.  of  20  per  cent,  phosphoric  acid  solution. 

B.  Connect  the  flask  to  a  glass  condenser  and  allow  the  outlet  of 
the  condenser  to  dip  beneath  the  surface  of  50  c.c.  of  N/20  iodine  solu- 
tion in  a  500-c.c.  Erlenmeyer  flask. 

C.  Add  not  over  1  gram  of  sodium  bicarbonate  to  the  distillation 
flask  and  quickly  insert  the  rubber  stopper  connecting  to  the  condenser. 
Distill  over  about  200  c.c.  into  the  flask  containing  the  iodine  solution. 
If  all  the  iodine  in  the  receiving  flask  is  discharged  before  the  distilla- 
tion is  complete  add  more  N/20  iodine  solution. 

D.  Add  a  few  drops  of  starch  indicator  to  the  distillate  and  titrate 
the  excess  iodine  with  N/20  sodium  thiosulphate  solution  until  the  blue 
color  just  disappears,  leaving  a  water-white  solution. 

E.  Report  the  sulphurous  acid  content  in  milligrams  per  kilogram 
(parts  per  million)  or  mgms.  per  liter  of  sample.    One  c.c.  N/20  iodine 
equals  .0016  gms.,  or  1.6  mgms.  sulphur  dioxide. 

8.  Preparation  of  Fehling's  Solutions: 

A.  Copper  Sulphate  Solution. — Dissolve  34.639  grams  of  C.P.  copper 
sulphate  (Cu  S04.  5H20)  in  water  and  dilute  to  500  c.c. 

B.  Alkaline  Tartrate  Solution. — Dissolve  173  grams  C.P.  or  U.  S.  P. 
Rochelle  salts  (sodium  potassium  tartrate)  and  50  grams  stick  sodium 
hydroxide  in  distilled  water  and  dilute  to  500  c.c.     Mix  and  allow  to 
settle. 

9.  Determination  of  Sugar: 

A.  Total  Sugar. — Preparing  the  Solution:  Weigh  exactly  an  amount 
of  sample  which  when  dissolved  in  distilled  water  and  diluted  to  500 
or  1,000  c.c.  in  a  volumetric  flask  will  give  a  solution  containing  not  more 
than  1  per  cent,  of  sugar. 

Liquid  products,  such  as  juices,  beverages  and  syrups,  are  merely 
diluted  without  heating.  Solid  materials,  such  as  fresh  or  dried  fruits, 
must  be  ground  thoroughly  before  sampling  and  the  weighed  sample 
boiled  vigorously  in  water  to  disintegrate  the  sample  and  extract  the 
sugar. 

In  the  case  of  dried  fruits,  a  representative  sample  of  1  pound  should 
be  ground  several  times  through  a  fine  food-chopper  with  a  nut-butter 
attachment,  10  grams  placed  in  a  1,000-c.c.  volumetric  flask  and  boiled 
vigorously  in  200  to  300  c.c.  distilled  water  for  15  to  20  minutes. 


FRUIT  AND  VEGETABLE 


101 


Clarifying  the  Solution:  Add  to  the  cooled  sugar  solution  small 
quantities  of  Home's  lead  sub-acetate  on  the  tip  of  a  knife-blade,  shak- 
ing after  each  addition  until  the  solution  clarifies  sharply;  that  is,  the 
solid  particles  settle  rapidly,  leaving  a  practically  clear  supernatant 
liquid.  Fill  to  the  mark  with  water,  mix  thoroughly  and  allow  to  stand 
overnight. 

Removing  Excess  Lead:  Mix  and  filter  about  50  c.c.  through  a  filter 
paper  and  add  sufficient  anhydrous  sodium  oxalate  to  precipitate  all 
excess  lead.  Mix  and  filter  again.  Test  the  filtrate  with  a  crystal  of 
sodium  oxalate  to  ascertain  if  free  of  lead. 

Inverting  the  Sucrose:  Pipette  25  c.c.  of  the  clear  filtrate  into  a 
250-c.c.  beaker,  add  about  5  c.c.  concentrated  hydrochloric  acid  and  10 
c.c.  water.  Heat  in  a  water  bath  at  about  70°C.  for  10  minutes.  Add 
a  few  drops  of  indicator  and  make  the  solution  approximately  neutral 
with  20  per  cent,  sodium  hydroxide  (about  10  c.c.  is  required). 

Precipitating  the  Cuprous  Oxide:  Add  25  c.c.  each  of  the  copper 
sulphate  and  alkaline  tartrate  solutions  described  in  8.  Cover  the 
beaker  with  a  watch-glass  and  heat  over  a  Bunsen  burner  so  that  boiling 
begins  in  about  4  minutes  and  continues  exactly  2  minutes.  Filter  at 
once  in  a  previously  dried  and  weighed  Gooch  crucible,  using  gentle 
suction.  (The  asbestos  should  be  digested  previously  with  acid  and 
alkali  and  washed  with  distilled  water.)  Wash  all  the  red  cuprous  oxide 
into  the  crucible  and  wash  with  hot  distilled  water  until  free  of  soluble 
salts.  Dry  the  crucible  in  an  oven  at  about  100°C.  for  an  hour  or 
longer,  cool  and  weigh. 

Calculating  the  Result:  From  the  weight  of  cuprous  oxide  obtained 
find  the  equivalent  weight  of  invert  sugar  from  Munson  and  Walker's 
Tables.1 

Example: 

Milligrams  of  cuprous  oxide  obtained  =  250.0 
Milligrams  of  invert  sugar  equivalent  to  =  116.4 
Milligrams  of  original  sample  represented 

25  c.c.    X10  grams)  =250.0 


\  1000  c.c.' 
Percentage  of  total  sugar  as  invert  sugar 
116.4 


2500  =  46-36  P01"  ccnt 

B.  Invert  Sugar  (Dextrose  and  Levulose).  —  In  products  containing 
only  invert  sugar,  such  as  grape  juice  or  raisins,  the  inversion  of  sucrose 
is  omitted. 


321,  Methods  Analysis  of  the;  Official  Agricultural  Chemist—  1920;  or  page  599, 
Food  Inflection  and  Analyws.-Lcach.  AGRICULTURAL  I  f 

" 


102  ;  'LABORATORY  MANUAL  OF 

C.  Cane  Sugar  (Sucrose). — In  products  containing  only  sucrose,  after 
inversion  and  determination  of  the  sucrose  as  invert  sugar,  the  percentage 
of  invert  sugar  multiplied  by  0.95  gives  the  percentage  of  sucrose  in  the 
sample. 

D.  Cane  Sugar  and  Invert  Sugar. — Where  it  is  desired  to  determine 
both  kinds  of  sugar  present  in  a  sample,  determine  (a)  Invert  sugar  in 
one  aliquot  without  inversion,  (b)  Total  sugar  in  another  aliquot  after 
inversion.    The  percentage  of  total  sugar  as  invert  sugar  minus  the  per- 
centage of  invert  sugar  obtained  without  inversion  gives  the  percentage 
of  invert  sugar  resulting  from  the  inversion  of  the  cane  sugar,  which, 
multiplied  by  0.95,  gives  the  percentage  of  cane  sugar  (sucrose). 

10.  Determination  of  Moisture: 

A.  Samples  Not  Containing  Invert  Sugar. — Weigh  exactly  10  grams 
of  finely  ground  sample  into  a  flat  tared  dish  and  dry  to  constant  weight 
in  an  oven  at  not  over  100°C.   (212°F.).     The  loss  in  weight  in  grams 
multiplied  by  10  gives  the  percentage  of  moisture. 

B.  Samples  Containing  Invert  Sugar,  such  as  Fruits,  Honey,  etc. — 
Proceed  as  in  10  A,  but  conduct  the  drying  for  12  hours  in  a  vacuum  oven 
at  70°C.  (158°F.)  and  not  over  4  inches  mercury  pressure. 

11.  Detection  of  Benzoate  of  Soda. — Acidify  the  sample,  such  as 
jam,  jelly,  catsup,  cider,  etc.,  with  dilute  sulphurous  acid,  after  diluting 
with  water  if  necessary.     Shake  in  a  separatory  funnel  with  an  equal 
volume  of  chloroform.    Draw  off  the  chloroform  layer  and  evaporate  it 
to  dryness  in  a  porcelain  dish.    Dissolve  the  residue  in  dilute  ammonia 
and  evaporate  to  dryness  over  a  water  bath.     Dissolve  the  residue  in 
a  small  amount  of  warm  water,  filtering  if  necessary.    Add  a  few  drops 
of  neutral  0.5  per  cent,  ferric  chloride  solution.    A  brownish  precipitate 
indicates  the  presence  of  benzoic  acid.     (A  violet  color  indicates  salicylic 
acid.) 

12.  Detection  of  Coal-tar  Dye. — Boil  a  strip  of  white  pure-wool 
yarn  or  cloth  for  5  to  15  minutes  in  a  20-  to  100-gram  sample  of  the 
product  diluted  with  an  equal  volume  of  water.    Remove  the  cloth  and 
rinse  thoroughly.    Acidify  the  diluted  sample  with  several  drops  of  con- 
centrated hydrochloric  acid  and  heat  again  with  another  piece  of  wool. 
Remove  the  cloth  and  rinse  thoroughly.    If  the  cloth  takes  up  any  con- 
siderable color  in  either  case,  the  presence  of  coal-tar  dye  is  indicated. 

Pure  Food  and  Drug  Regulations  permit  the  use  of  the  following 
eight  certified  colors  in  food  products,  if  labeled  "artificially  colored": 
Orange  I,  Erythrosine,  Indigo  Carmine,  Amaranth,  Tartrazine,  Napthol 
Yellow  S,  Ponceau  3  R,  Light  Green  S.  F.  Yellowish.  For  the  separation 
and  identification  of  these  and  non-permissible  coal-tar  dyes,  see 
"Methods  of  Analysis  of  the  Association  of  Official  Agricultural  Chem- 
ists, Washington,  D.  C." 


FRUIT  AND  VEGETABLE  PRODUCTS 


103 


TABLE  XIII. — TEMPERATURE  CORRECTIONS  FOR  BALLING  HYDROMETER. 

To  use  the  table,  the  apparent  sugar  percentage  (Balling  degree)  of  the  syrup  is 
determined  by  hydrometer  and  the  temperature  observed.  Opposite  the  indicated 
temperature  and  in  the  column  below  the  indicated  sugar  percentage  will  be  found  the 
amount  to  be  added  or  subtracted  from  the  observed  reading. 

Example: 

Observed  sugar 50  per  cent. 

Observed  temperature 115°  F. 

Opposite  115°  F.  and  below  50  per  cent  is  found  2.32.  This  is  then  added  to  50 
per  cent,  making  52.32,  corrected  Balling  degree. 


Temp. 
Fahr. 

Temp. 
Cent. 

10° 

20° 

30° 

40°            60° 

75° 
Balling 

Corrections  to  be  subtracted  from  degrees  Balling 

32 

0 

.41 

.62 

.82 

.98 

1.22 

1.29 

41 

5 

.37 

.52 

.65 

.75 

.88 

.94 

50 

10 

.29 

.36 

.42 

.49 

.54 

.61 

54 

12.2 

.22 

.26 

.31 

.34 

.40 

.46 

57 

13.9 

.16 

.18 

.21 

.22 

.26 

.32 

61 

16.1 

.08 

.10 

.11 

.12    . 

.14 

.18 

62 

16.7 

.03 

.03 

.04 

.04 

05 

.06 

Corrections  to  be  added  to  degrees  Balling 

64 

17.78 

.03 

.03 

.03 

.03 

.03            .02 

68 

20.00 

.08 

.09 

.10 

.10 

.10 

.06 

72 

22.33 

.29 

.31 

.32 

.33 

.32 

.25 

75 

23.89 

.41 

.44 

.46 

.47 

.46 

.40 

79 

26.11 

.54 

.58 

.61 

.62 

.62 

.55 

82 

27.78 

.68 

.72 

.76 

.78 

.78 

.70 

86 

30.00 

.82 

.92 

.94 

.98 

.88 

.86 

90 

32.23 

.98 

1.03 

1  08 

1.10 

1.10 

.98 

93 

33.89 

1.14 

1.21 

1.24 

1.28 

1.26 

1.17 

97 

36.11 

1.32 

1.38 

1.41 

1.46 

1.42 

1  33 

100 

37.78 

1.49 

1.55 

1.59 

1.64 

1.60 

1.49 

104 

40  00 

1.67 

1.73 

1.79 

1.82 

1.78 

1.65 

108 

42.23 

1.86 

1.93 

1.99 

2.00 

1.96 

1.81 

110 

43.34 

1.96 

2.03 

2.09 

2.10 

2.05 

1.89 

112 

44.45 

2.06              2.13 

2.19 

2  20 

2.14 

1  97 

115 

46.11 

2.27              2.34 

2.39 

2  40 

2.32 

2.35 

117 

47.23 

2.38             2.45 

2.49 

2.50 

2.41 

2.24 

119 

48.34 

2.49 

2.56 

2.59 

2.60 

2.50 

2  23 

121 

49.45 

2  60 

2.67 

2.69 

2.70 

2.60 

2.42 

112 

50.00 

2  71 

2.78 

2.80 

2.80 

2  70 

2.51 

124 

51.11 

2.81 

2.89 

2.90 

2  91 

2.80 

2.60 

126 

52.23 

2.92 

3  00 

3.01 

3.02 

2.90 

2.69 

I2S 

53.34 

3.03             3.11 

3.12 

3.13 

3.00 

2.78 

130 

54.45 

3.14             3  .  22 

3.23 

3  24 

3.10 

2.87 

131 

55.00 

3.26 

3.33 

3.33 

3.29 

3  20 

2  93 

133 

66.11 

3.39 

3.44 

3.44 

3.46 

3.30 

3  05 

135 

57.23 

3.52 

3  55 

3  55 

3  57 

3  40 

3  14 

137 

58  34 

3.64 

3  66 

3.66 

3.68 

3.50 

3.23 

139 

59  45 

3.76 

3.77 

3.77 

3.79 

3.60 

3.32 

140 

60.00 

3.82 

3.88 

3.88 

3.90 

3.70 

3  41 

149 

65.00 

4  53 

4  51 

4.49 

4.48 

4.21 

3.88 

158 

70  00 

5.18 

5.14 

5  10 

5.06 

4  32 

4  35 

167 

75.00 

6.00 

5.84 

5.74 

5  .  66 

5  27 

4.84 

176 

80  00 

6.62 

6.64 

6.38 

6  .  26 

6.82 

5  33 

185 

85.00 

7.44              7.30 

7.10 

6  92 

6.39 

5  85 

194 

90.00 

8  .  26             8  06 

7.85 

7.68       <;  r>s 

6  37 

203 

95  00 

9  14             8.89 

8.61 

835          7  •)«.) 

6  90 

212 

100.00 

10.10             9.72 

9.39 

9  03 

8  .  22 

7  42 

104 


LABORATORY  MANUAL  OF 


TABLE  XIV. — RELATION  OF  SPECIFIC  GRAVITY,  BATTM^  AND  BALLING  READINGS  OF 

SALT,  SUGAR  AND  SODA  LYE  SOLUTIONS  AT  20°C.  (68°F.) 

(From  Cruess,  Home  and  Farm  Food  Preservation) 


Spec, 
grav. 

Salt 

Sugar 

Soda  lye 

Baum6 
degree 

Oz.*  per 
gal. 

Balling, 
per  cent 
sugar 

Oz.*  per 
gal. 

Per  cent 

Oz.*per 
gal. 

1.007 

1 

1.3 

1.8 

2.3 

0.5 

0.7 

1.014 

2 

2.6 

3.6 

4.8 

1.2 

1.5 

1.022 

3 

4.0 

5.5 

7.5 

1.8 

2.4 

1.029 

4 

5.3 

7.2 

9.9 

2.5 

3.2 

1.036 

5 

6.7 

9.0 

12.6 

3.1 

4.1 

1.045 

6 

8.1 

10.8 

15.5 

3.7 

5.0 

1.052 

•7 

9.6 

12.6 

18.5 

4.5 

6.0 

1.060 

8 

11.1 

14.5 

21.7 

5.2 

7.0 

1.067 

9 

12.7 

16.2 

24.7 

5.8 

8.0 

1.075 

10 

14.2 

18.1 

28.3 

6.6 

9.0 

1.083 

11 

15.8 

19.8 

31.6 

7.3 

10.1 

1.091 

12 

17.5 

21.7 

35.5 

8.1 

11.3 

1.100 

13 

19.1 

23.5 

39.3 

8.8 

12.4 

1.108 

14 

20.8 

25.3 

43.3 

9.5 

13.5 

1.116 

15 

22.6 

27.2 

47.8 

10.3 

14.7 

1.125 

16 

24.4 

29.1 

52.5 

11.1 

15.9 

1.134 

17 

26.2 

30.9 

57.2 

11.9 

17.3 

1.142 

18 

28.1 

32.7 

62.2 

12.7 

18.6 

1.152 

19 

30.0 

34.6 

67.7 

13.5 

19.9 

1.162 

20 

32.0 

36.5 

73.6 

14.3 

21  3 

1.171 

21 

34.0 

38.3 

79.5 

15.1 

22.7 

1.180 

22 

36.1 

40.1 

85.7 

16.0 

24.2 

1.190 

23 

38.2 

42.0 

92.7 

16.9 

25.7 

1.200 

24 

40.4 

43.9 

100.2 

17.8 

27.3 

1.210 

25 

42.7 

45.9 

108.6 

18.7 

29.0 

1.220 

26 

45.0 

47.7 

116.7 

19.6 

30.7 

1.231 

27 

47.3 

49.6 

126.0 

20.6 

32.5 

1.241 

28 

49.8 

51.6 

136.5 

21.5 

34.2 

1.252 

29 

52.3 

53.5 

147.3 

22.5 

36.1 

1.263 

30 

54.9 

55.4 

159.0 

23.5 

38.0 

1.274 

31 

57.5 

57.3 

171.8 

24.5 

39.9 

1.285 

32 

60.2 

59.3 

186.5 

25.5 

41.9 

1.297 

33 

63.0 

61.2 

201.9 

26.6 

44.1 

1.308 

34 

66.0 

63.2 

219.8 

27.6 

46.3 

1.320 

35 

69.0 

65.2 

240.0 

28.8 

48.7 

1.332 

36 

72.0 

67.2 

262.2 

30.0 

51.1 

1.345 

37 

75.2 

69.2 

287.6 

31.2 

53.7 

1.361 

38 

78.4 

71.2 

316.4 

32.4 

56.4 

Ounces  of  material  to  be  added  to  one  gallon  of  water. 


FRUIT  AND  VEGETABLE  PRODUCTS 


105 


TABLE  XV. — MINIMUM  DRAINED  WEIGHTS  FOR  CANNED  FRUITS  AND  VEGETABLES 

The  following  minimum  drained  weights  have  been  adopted  by  the  United  States 
Department  of  Agriculture,  Bureau  of  Chemistry,  in  the  enforcement  of  the  Pure  Food 
and  Drugs  Act.  In  each  case,  the  drained  or  "cut-out"  weight  is  obtained  by  drain- 
ing the  contents  of  the  can  on  a  piece  of  1/8-inch  mesh  screen  for  2  minutes.  The 
proper  filling  of  canned  fruits  and  vegetables  not  mentioned  in  this  table  is  determined 
by  visual  inspection,  no  definite  weights  having  been  found  practicable. 


Material 

Size  of  can 
No. 

Drained  weight  (ozs.) 

Remarks 

Beans,  Wax  and  Refugee. 
Beans,  green  lima  

1 
2 
2 
10 
10 
1 

6 

11H 

12 
61 
65 

8 

Whole  beans 
Cut  beans 
Whole  beans 
Cut  beans 

Cherries,  unpitted  

2 
10 
1 

13^ 
72 
IQYz 

Cherries,  pitted  

2 
2 
2H 
2K 
10 
10 
1 

12 
13 

18 
19 
68 
72 
IVz 

Syrup  cut-out  above  20° 
Syrup  cut-out  below  20° 
Syrup  cut-out  above  20° 
Syrup  cut-out  below  20° 
Syrup  cut-out  above  20° 
Syrup  cut-out  below  20° 
Syrup  cut-out  above  20° 

Corn,  Maryland  style.  .  .  . 
Peaches,  halves  or  slices  . 

Pears  

2 
2 
2H 
2H 
10 
2 
1 
2 
2^ 
10 
1 

12J4 
13H 
18H 
19M 
70 
13H 
10H 
13H 
20 
68 
10-1/2 

Syrup  cut-out  below  20° 
Syrup  cut-out  above  20° 
Syrup  cut  out  above  20° 
Syrup  cut-out  below  20° 
Packed  in  water 

Not  pie  fruit 

Peas,  

2 

2y2 

3 
10 
1 

13 
19 
22 
67 
I'M 

Sauerkraut  

2 
10 
2 

IVA 
72 
16 

Spinach  

2H 
3 
10 
2 

23 

27 
80 
13 

2H 
3 
10 

19 

21H 

66 

106  LABORATORY  MANUAL 

TABLE  XVI. — RELATION  OF  THE  BOILING  POINT  OF  WATER  TO  VACUUM. 


Vacuum  in. 
Mercury 

Temp. 
0  Fahr. 

Vacuum  in. 
Mercury 

Temp. 
0  Fahr. 

Vacuum  in. 
Mercury 

Temp. 

0  Fahr. 

29.0 

79.07 

19.0 

165.42 

9.0 

104.52 

28.0 

101.15 

18.0 

169.14 

8.0 

196.73 

27.0 

115.06 

17.0 

172.63 

7.0 

198.87 

26.0 

125.38 

16.0 

175.93 

6.0 

200.94 

25.0 

133  .  77 

15.0 

179.03 

5.0 

202.92 

24.0 

140.64 

14.0 

181.92 

4.0 

204.85 

23.0 

146.78 

13.0 

184.68 

3.0 

206.71 

22.0 

152.16 

12.0 

187.31 

2.0 

208.52 

21.0 

157.00 

11.0 

189.83 

1.0 

210.28 

20.0 

161.42 

10.0 

192.23 

0.0* 

212.00 

*  Zero  vacuum  is  atmospheric  pressure  or  14.7  Ib.  absolute  pressure. 

TABLE  XVII. — BOILING  POINT  OF  WATER  AT  DIFFERENT  ALTITUDES 
ABOVE  SEA  LEVEL. 


Boiling  Point 

Boiling  Point 

Boiling  Point 

Altitude 

Altitude 

Altitude 

(Feet) 

•F. 

•c. 

(Feet) 

i. 

•a 

(Feet) 

•r. 

•c. 

0 

212 

100 

4169 

204 

96 

7381 

197 

92 

1025 

210 

99 

5225 

202 

94 

8481 

196 

91 

2063 

208 

98 

6304 

200 

93 

9031 

195 

90 

3115 

206 

97 

TABLE  XVIII. — SIZE  AND  CAPACITY  OF  STANDARD  SANITARY  CANS  USED  FOR 
FRUITS  AND  VEGETABLES. 


Number  of  Can 

Diameter  in  Inches 

Height  in  Inches 

Capacity  in  Fluid 
Ounces 

1  (Eastern  Oyster)  .  .  . 
1  Tall  Calif  

2% 
3 

4 

4% 

12 
12 

1  Flat  Calif  

4 

2% 

16 

2      

3% 

V/z 

21 

2H      

4 

4% 

31 

3    

4^ 

4K 

35 

10  

6>g 

7 

107 

12                  

§1A 

8% 

128 

SELECTED  REFERENCES 

Canning 

Bigelow,  W.  D.,  Swells  and  Springers,  Bull.  2,  National  Canners  Association. 
Bigelow,  W.  D.,  Heat  Penetration  in  Processing  Canned  Foods,  Bull.  16L,  National 

Canners  Association. 
Bigelow,  W.  D.,  Springers  and   Perforations  in   Canned   Fruits,   Circ.    1L,    National 

Canners  Association. 
Bigelow,  W.  D.,  and  Cathcart,  P.  II.,  Relation  of  Processing  to  the  Acidity  of  Canned 

Foods,  Bull.  17L,  National  Canners  Association. 

Bitting,  A.  W.,  Preliminary  Bulletin  on  Canning,  Bull.  1,  National  Canners  Association. 
Bitting,  A.  W.,  Methods  Followed  in  the  Commercial  Canning  of  Foods,  Bull.  1%, 

Bureau  of  Chemistry,  U.  S.  Dept.  of  Agr. 

Bitting,  A.  W.,  Exhaust  and  Vacuum,  Bull.  8,  National  Canners  Association. 
Bittina,  A.  W.,  Processing  and  Process  Devices,  Bull.  9,  National  Canners  Association. 
Bitting,  A.  W.,  Washing  Fruits  and  Vegetables,  Bull.  12,  National  Canners  Association. 
Bitting,  A.  W.,  and  Bitting,  K.  G.,  Bacteriological  Examination  of  Canned  Foods. 

Bull.  14,  National  Canners  Association. 

Bitting,  K.  G.,  Lye  Peeling,  Bull.  10,  National  Canners  Association. 
Magoon,  C.  A.,  and  Culpepper,  C.  W.,  A  Study  of  the  Factors  Affecting  Temperature 

Changes  in  the  Container  during  the  Canning  of  Fruits  and  Vegetables,  Bull. 

956,  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agr. 
Magoon,  C.  A.,  and  Culpepper,  C.  W:,  Relation  of  Initial  Temperature  to  Pressure, 

Vacuum  and  Temperature  Changes  in  the  Container  during  Canning  Operations, 

Bull.  1022,  Bureau  of  Plant  Industry,  U.  S.  Dept.  of  Agr. 
Zavalla,  J.  P.,  The  Canning  of  Fruits  and  Vegetables,  John  Wiley  and  Sons. 
—  A  Complete  Course  in  Canning,  The  Canning  Trade,  Baltimore. 
-  Home  Canning  of  Fruits  and  Vegetables,  Farmers  Bull.  1211,  U.  S.  Dept. 

of  Agr. 

Canning  Journals 
The  Canner,  Chicago. 
The  Canning  Age,  New  York. 
The  Canning  Trade,  Baltimore. 

Tomato  Products 
Bigelow,  W.   D.,  and  Fitzgerald,   F.   F.,  Tomato  Pulp,   Bull.  3,  National  Canners 

Association. 
Bigelow,  W.  D.,  and  Fitzgerald,  F.  F.,  Specific  Gravity  and  Solids  in  Tomato  Pulp, 

Bull.  7,  National  Canners  Association. 
Hier,  W.  G.,  The  Manufacture  of  Tomato  Products,  Brock-Hoffner  Press  Company, 

Denver. 
Howard,  B.  J.,  Sanitary  Control  of  Tomato  Canning  Factories,  Bull.  569,  IT.  S.  Dept. 

of  Agr. 
Howard,  B.  J.,  and  Stephensoo,  C.  II.,  Microscopical  Studies  on  Tomato  Products, 

Hull.  5«1,  IT.  S.  Dept,  of  Agr. 

107 


108  LABORATORY  MANUAL  OF 

Fruit  Juices 

Caldwell,  J.  S.,  Studies  in  the  Clarification  of  Unfermented  Fruit  Juices,  Bull.  1025, 
U.  S.  Dept.  of  Agr. 

Cruess,  W.  V.,  Unfermented  Fruit  Juices,  Circ.  220,  University  of  Calif.  Experiment 
Station. 

Dearing,  Chas.  T.,  Unfermented  Grape  Juice,  Farmers  Bull.  1075,  U.  S.  Dept.  of  Agr. 

Gore,  H.  C.,  Unfermented  Apple  Juice,  Bull.  118,  Bureau  of  Chemistry,  U.  S.  Dept. 
of  Agr. 

Gore,  H.  C.,  Studies  on  Fruit  Juices,  Bull.  241,  U.  S.  Dept.  of  Agr. 

Hartmann,  B.  G.,  and  Tolman,  L.  M.,  Concord  Grape  Juice:  Manufacture  and  Chemical 
Composition,  Bull.  656,  U.  S.  Dept.  of  Agr. 

Lewi.0,  C.  I.  ,  and  Brown,  F.  R.,  Loganberry  By-products,  Bull.  118,  Oregon  Experi- 
ment Station. 

Walker,  S.  S.,  and  McDermott,  A.  F.,  The  Utilization  of  Cull  Citrus  Fruits  in  Florida, 
Bull.  135,  Florida  Experiment  Station. 

Fruit  Syrups 

Bioletti,  F.  T.,  and  Cruess,  W.  V.,  Grapt  Syrup,  Bull.  303,  University  of  Calif.  Experi- 
ment Station. 

Cruess,  W.  V.,  Commercial  Production  of  Grape  Syrup,  Bull.  321,  University  of  Calif. 
Experiment  Station. 

Dearing,  C.  T.,  Muscadine  Grape  Syrup,  Farmers  Bull.  758,  U.  S.  Dept.  of  Agr. 

Gore,  H.  C.,  Apple  Syrup  and  Concentrated  Cider,  Year  Book  Separate  639  (1914), 
U.  S.  Dept.  of  Agr. 

Hausbrand,  E.,  Evaporating,  Condensing  and  Cooling  Apparatus,  Scott,  Greenwood 
and  Son,  London. 

Jelly  and  Marmalade 
Caldwell,  J.  S.,  A  New  Method  for  the  Preparation  of  Pectin,  Bull.  147,  Washington 

Agr.  Experiment  Station. 
Cruess,  W.  V.,  Jellies  and  Marmalades  from  Citrus  Fruits,  Circ.  146,  University  of 

Calif.  Experiment  Station. 
Goldwaithe,  N.  E.,  Principles  of  Jelly  Making,  Lesson  114,  Food  Series,  Cornell  Agr. 

College  Reading  Course. 
Goldwaithe,  N.  E.,  A  Contribution  on  the  Chemistry  and  Physics  of  Jelly  Making, 

Journal,  Industrial  and  Engineering  Chemistry,  1909,  pg.  333 
Powell,  Ola,  Successful  Canning  and  Preserving,  J.  B.  Lippincott  Co.,  Philadelphia, 

Publishers. 

Jam,  Preserves,  Butter  and  Paste 

Abell,  T.  H.,  Apple  Candy,  Bull.  179,  Utah  Experiment  Station. 
Close,  C.  P.,  Homemade  Fruit  Butters,  Farmers  Bull.  900,  U.  S.  Dept.  of  Agr. 
Dearing,  C.  T.,  Muscadine  Grape  Paste,  Farmers  Bull.  1033,  U.  S.  Dept.  of  Agr. 
Pacrettc,  J.,  The  Art  of  Canning  and  Preserving,  Jules  H.  Dommergue,  Jersey  City, 

N.  J.,  Publisher. 

Potts,  A.  T.,  The  Fig  in  Texas,  Bull.  208,  Texas  Experiment  Station. 
Powell,  Ola,  Successful  Canning  and  Preserving,  J.  B.  Lippincott  Co.,  Philadelphia. 

Dried  Fruits  and  Vegetables 
Beattie,  J.  H.,  and  Gould,  H.  P.,  Commercial  Evaporation  and  Drying  of  Fruits, 

Farmers  Bull.  903,  U.  S.  Dept.  of  Agr. 
Caldwell,  J.  S.,  The  Evaporation  of  Fruits  and  Vegetables,  Bull.  148,  Washington 

Experiment  Station. 


FRUIT  AND  VEGETABLE  PRODUCTS  109 

Caldwell,  J.  S.,  Farm  and  Home  Drying  of  Fruits  and  Vegetables,  Fanners  Bull.  984, 

U.  S.  Dept.  of  Agr. 
Cruess,  W.  V.,  and  Christie,  A.  W.,  The  Dehydration  of  Fruits,  Bull.  330,  University 

of  Calif.  Experiment  Station. 
Cruess,  W.  V.,  and  Christie,  A.  W.,  Some  Factors  Affecting  Dehydrater  Efficiency, 

Bull.  387,  University  of  Calif.  Experiment  Station 
Cruess,  W.  V.,  and  Christie,  A.  W.,  The  Evaporation  of  Grapes,  Bull.  322,  University 

of  Calif.  Experiment  Station. 

Hausbrand,  E.,  Drying  by  Means  of  Air  and  Steam,  Scott,  Greenwood  and  Son,  London. 
Parker,  W.  B.,  Control  of  Dried  Fruit  Insects  in  California,  Bull.  235,  Bureau  of  Ent., 

U.  S.  Dept.  of  Agr. 
Prescott,  S.  C.,  Relation  of  Dehydration  to  Agriculture,  Circ.  126,  Office  of  Secretary, 

U.  S.  Dept.  of  Agr. 
Tiemann,  H.  D.,  The  Kiln  Drying  of  Lumber,  J.  B.  Lippincott  Co.,  Philadelphia. 

Fixed  and  Essential  Oils 
Hood,  C.  S.,  and  Russell,  G.  A.,  The  Production  of  Sweet  Orange  Oil  and  a  New  Machine 

for  Peeling  Citrus  Fruits,  Department  Bull.  399,  IT.  S.  Dept.  of  Agr. 
Powell,  G.  H.,  and  Chace,  E.  M.,  Italian  Lemons  and  their   By-products,  Bull.  160, 

Bur.  Plant,  Ind.,  U.  S.  Dept.  of  Agr. 
Rabak,  F.,  Commercial  Utilization  of  Grape  Pomace  and  Stems  from  the  Grape  Juice 

Industry,  Department  Bull.  952,  U.  S.  Dept.  of  Agr. 
Rabak,  F.,  The  Utilization  of  Cherry  By-products,  Department  Bull.  350,  U.  S.  Dept. 

of  Agr. 
Rabak,  F.,  The  Utilization  of  Waste  Tomato  Seeds  and  Skins,  Department  Bull.  632, 

U.  S.  Dept.  of  Agr. 
Rabak,  F.,  Peach,  Apricot  and  Prune  Kernels  as  By-products  of  the  Fruit  Industry 

of  the  United  States,  Bull.  133,  Bur.  Plant 'ind.,  U.  S.  Dept.  of  Agr. 
Rabak,  F.,  The  Utilization  of  Waste  Raisin  Seeds,  Bull.  276.  Bur.  Plant   Ind.,  U.  S. 

Dept.  of  Agr. 

Vinegar  and  Pickles 
Cruess,  W.  V.,  Vinegar  from  Waste  Fruits,  Bull.  287,  University  of  Calif.  Experiment 

Station. 

Le  Fevre,  E.,  Fermented  Pickles,  Farmers  Bull.  1159,  IT.  S.  Dept.  of  Agr. 
Round,  L.  A.,  and  Lang,  H.  L.,  Preservation  of  Vegetables  by  Fermentation  and 

Salting,  Farmers  Bull.  881,  U.  S.  Dept.  of  Agr. 
Wyant,  Z.  N.,  Vinegar,  Special  Bull.  98,  Michigan  Experiment  Station. 

Methods  of  Analysis 

Leach,  A.  E.,  Food  Inspection  and  Analysis,  John  Wiley  &  Sons,  N.  Y.  City. 
Leach,  A.  E.,  Methods  of  Analysis,  Association  of  Official  Agricultural  Chemists,  Wash- 
ington, D.  C. 


ITY  of  CALIFORNIA 

AT 

GELES      • 
Y 


TX603 

C8 

1922 


Cruess,  William  Vere 

Laboratory  manual  of  fruit 
and  vegetable  products. 


UC  SOUTHERN  REGIONW.  LIBRARY FACIL  TV 


A    001  445  827    7 


AGRICULTURAL  LIBRARY 

UNIVERSITY  OF  CALIFORNIA 

CITRUS  RESEARCH  CENTER  AND 
AGRILULYU.  Al  EXPERIMENT  STATION 
.£.  CALIFORNIA 


